JP2006186765A - Radio base station, inter-radio base station synchronization control center, and synchronization control method for inter-radio base station synchronization control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio base station, an inter-radio base station synchronization control center, and a synchronization control method for an inter-radio base station synchronization control system, enabling restoration of frame synchronization when the frame synchronization fails. <P>SOLUTION: A frame synchronization controller 33 synchronizes a frame of the self-station with a reference signal from a GPS antenna 30. A communication state information generator 21 generates communication state information representing the communication state of the self-station, so as to transmit to the inter-radio base station synchronization control center 1. A frame resynchronization controller 3 decides whether frame resynchronization is required in each radio station based on the received communication state information of each radio base station, and transmits an instruction for frame resynchronization to the radio base station in which the frame resynchronization is required. On receipt of the instruction for frame resynchronization, a frame synchronization controller 33 performs frame synchronization of the self-station again. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio base station, a radio base station synchronization control center, and a synchronization control method for a radio base station synchronization control system.

  In a mobile communication system (for example, Personal Handy-Phone System: PHS), communication is performed by a TDMA / TDD (Time Division Multiple Access / Time Division Duplex) method.

  FIG. 8 is a diagram for explaining the TDMA / TDD system.

  In PHS, one frame is composed of 8 slots, and is composed of 4 slots (communication direction from the radio terminal station to the radio base station) and 4 slots (communication direction from the radio base station to the radio terminal station). Usually, a common control channel (hereinafter, referred to as a common control channel) is assigned to each pair of radio terminal stations among the four pairs of uplink and downlink slots, and each radio is assigned to three pairs of slots. Separate control channels (hereinafter referred to as individual control channels) and speech channels are allocated at the terminal station. In addition, the radio base station and the radio terminal station transmit and receive radio signals of one or a plurality of bands, and there are frames and slots for each of these bands (hereinafter referred to as radio channels).

  By the way, a process called frame synchronization is performed between a plurality of base stations in order to improve frequency utilization efficiency and prevent interference.

  For example, in Patent Document 1, one base station transmits a synchronization signal serving as a time reference to each slave station, each slave station detects the synchronization signal, uses this as a time reference, and is assigned to the own station. Each communication line is captured by checking the time positions of the downlink (circuit receiving a signal transmitted from the base station) and the uplink (circuit transmitting a signal to the base station). As a result, frame synchronization is established between the radio stations.

FIG. 9 is a diagram illustrating a state in which frame synchronization is established in the radio base stations A, B, and C. By such frame synchronization, radio wave interference between radio base stations can be prevented, effective use of frequencies, and good communication quality can be maintained.
JP-A-6-338854

  However, in a certain radio base station, frame synchronization once established may not be established due to the accuracy of the device or noise superimposed on the synchronization signal.

FIG. 10 is a diagram illustrating a state in which the radio base station B has lost frame synchronization.
As shown in FIG. 10, when the radio base station B is out of frame synchronization, the radio base station B becomes an interference source for the radio base stations A and C.

  Further, all the surrounding radio base stations including the radio base stations A and C are interference sources for the radio base station B. For example, the frequency f1 is in the first slot of the radio base station A, the frequency f2 is in the fourth slot of the radio base station A, the frequency f3 is in the first slot of the radio base station C, and the frequency f4 is in the fourth slot of the radio base station C. If used, the first slot of the radio base station B will receive direct interference regardless of the frequency of f1 to f4. Therefore, a frame error rate (FER: Frame Error Rate) representing the occurrence rate of frames that cause errors in the radio base station B is larger than the frame error rates of the radio base stations A and C.

  Therefore, the present invention provides a radio base station, an inter-radio base station synchronization control center, and an inter-radio base station synchronization control system that can recover the frame synchronization when the frame synchronization is lost. That is.

  In order to solve the above problems, the radio base station of the present invention represents a frame synchronization unit that synchronizes its own frame with a reference signal from a GPS antenna or a frame of another radio base station, and a communication state of the own station. A communication state information creating unit that creates communication state information, and a communication unit that transmits the communication state information to the inter-radio base station synchronization control center and receives a reframe synchronization instruction from the inter-radio base station synchronization control center, When receiving a re-frame synchronization instruction from the inter-radio base station synchronization control center, the frame synchronization unit synchronizes its own frame again.

  Preferably, the communication state information creating unit creates communication state information representing the traffic amount within a predetermined time and the number of errors or error rate within the predetermined time.

  The inter-radio base station synchronization control center of the present invention is an inter-radio base station synchronization control center that controls frame synchronization between a plurality of radio base stations, and each radio base station communicates with the radio base station. A communication unit that receives communication state information indicating a state, and a reframe synchronization control unit that determines whether or not each radio base station needs reframe synchronization based on the received communication state information of each radio base station. The communication unit transmits a reframe synchronization instruction to the radio base station determined to require reframe synchronization.

  Preferably, the communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within a predetermined time, and the reframe synchronization control unit is configured such that the communication state information includes a predetermined amount of traffic within the predetermined time. When the number of errors within a predetermined time exceeds a threshold and the number of errors within a predetermined time exceeds the predetermined number, indicating that the number of errors exceeds a predetermined value than the number of errors within a predetermined time of another radio base station Therefore, it is determined that reframe synchronization is necessary.

  Preferably, the communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within a predetermined time, and the reframe synchronization control unit is configured such that the communication state information includes a predetermined amount of traffic within the predetermined time. When the error rate within the predetermined time exceeds the threshold and the error rate within the predetermined time exceeds the predetermined number, indicating that the error rate within the predetermined time of the other radio base station exceeds the predetermined value. Therefore, it is determined that reframe synchronization is necessary.

  Also, the synchronization control method of the inter-radio base station synchronization control system of the present invention is a radio comprising a plurality of radio base stations and an inter-radio base station synchronization control center for controlling frame synchronization between the plural radio base stations. A synchronization control method for an inter-base station synchronization control system, wherein each radio base station synchronizes its own frame with a reference signal from a GPS antenna or a frame of another radio base station, and each radio base station A communication state information creating step for creating communication state information representing a communication state of the own station, a step in which each wireless base station transmits communication state information to a synchronization control center between wireless base stations, and synchronization control between wireless base stations A step in which the center receives communication state information indicating a communication state of the radio base station from each radio base station; and a communication status of each radio base station received by the inter-radio base station synchronization control center. Based on the information, a reframe synchronization control step for determining whether or not each radio base station needs reframe synchronization, and a radio base station synchronization control center to a radio base station determined to require reframe synchronization A step of transmitting a reframe synchronization instruction; and when each radio base station receives a reframe synchronization instruction from the inter-radio base station synchronization control center, the reference signal from the GPS antenna or another radio base station is again transmitted. Synchronizing the frame of the local station to the frame of the local station.

  Preferably, in the communication status information creation step, each radio base station creates communication status information indicating the traffic volume within a predetermined time and the number of errors or error rate within the predetermined time, and in the reframe synchronization control step, The inter-radio base station synchronization control center has a communication status information in which the amount of traffic within a predetermined time exceeds a specified value, the number of errors within a predetermined time exceeds a threshold, and the number of errors within a predetermined time exceeds a predetermined number. It is determined that reframe synchronization is necessary when it indicates that the number of errors in the radio base station is greater than the predetermined number of errors within a predetermined time.

  Preferably, in the communication status information creation step, each radio base station creates communication status information indicating the traffic volume within a predetermined time and the number of errors or error rate within the predetermined time, and in the reframe synchronization control step, The inter-radio base station synchronization control center has a communication status information in which a traffic amount within a predetermined time exceeds a specified value, an error rate within a predetermined time exceeds a threshold, and an error rate within a predetermined time exceeds a predetermined number. It is determined that reframe synchronization is necessary when it indicates that the error rate within a predetermined time of the wireless base station is greater than a predetermined value.

  In addition, the inter-radio base station synchronization control system of the present invention includes an inter-radio base station synchronization system comprising a plurality of radio base stations and an inter-radio base station synchronization control center that controls frame synchronization between the radio base stations. In this control system, each radio base station has a frame synchronization unit that synchronizes its own frame with a reference signal from a GPS antenna or a frame of another radio base station, and communication status information indicating the communication status of the own station. A communication state information creation unit to be created, and a communication unit that transmits the communication state information to the inter-radio base station synchronization control center and receives a re-frame synchronization instruction from the inter-radio base station synchronization control center. When the reframe synchronization instruction is received from the inter-radio base station synchronization control center, the own frame is synchronized again. The inter-radio base station synchronization control center A communication unit that receives communication state information indicating a communication state of each of the radio base stations, and a re-transmission unit that determines whether or not each radio base station needs reframe synchronization based on the received communication state information of each radio base station. A frame synchronization control unit, and the communication unit transmits a reframe synchronization instruction to the radio base station determined to require reframe synchronization.

  Preferably, the communication state information creating unit creates communication state information indicating the traffic amount within a predetermined time and the number of errors or the error rate within the predetermined time, and the reframe synchronization control unit is configured so that the communication state information is predetermined. The amount of traffic in the time exceeds the specified value, the number of errors in the predetermined time exceeds the threshold, and the number of errors in the predetermined time exceeds the predetermined number. It is determined that reframe synchronization is necessary when it indicates that the number of frames exceeds the threshold.

  Preferably, the communication state information creating unit creates communication state information indicating the traffic amount within a predetermined time and the number of errors or the error rate within the predetermined time, and the reframe synchronization control unit is configured so that the communication state information is predetermined. The amount of traffic in the time exceeds the specified value, the error rate in the predetermined time exceeds the threshold, and the error rate in the predetermined time exceeds the predetermined number. It is determined that reframe synchronization is necessary when it indicates that it is larger than.

  In addition, the radio base station synchronization control program of the present invention synchronizes the frame of the local station with the reference signal from the GPS antenna or the frame of another radio base station in order to control the synchronization of the radio base station. A frame synchronization unit, a communication state information creation unit that creates communication state information indicating the communication state of the own station, and the communication state information is transmitted to the inter-radio base station synchronization control center, and re-framed from the inter-radio base station synchronization control center. The frame synchronization unit functions as a communication unit that receives the synchronization instruction, and the frame synchronization unit synchronizes the frame of the own station again when receiving the reframe synchronization instruction from the radio base station synchronization control center.

  Preferably, the communication state information creating unit creates communication state information representing a traffic amount within a predetermined time and an error count or an error rate within the predetermined time.

  In addition, the control program for the inter-radio base station synchronization control center controls the inter-radio base station synchronization control center for controlling the frame synchronism between a plurality of radio base stations. A communication unit that receives communication state information indicating a communication state of a radio base station, and a reframe that determines whether or not each radio base station needs reframe synchronization based on the received communication state information of each radio base station The communication unit functions as a synchronization control unit, and transmits a reframe synchronization instruction to the radio base station determined to require reframe synchronization.

  Preferably, the communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within a predetermined time, and the reframe synchronization control unit is configured such that the communication state information includes a predetermined amount of traffic within the predetermined time. When the number of errors within a predetermined time exceeds a threshold and the number of errors within a predetermined time exceeds the predetermined number, indicating that the number of errors exceeds a predetermined value than the number of errors within a predetermined time of another radio base station Therefore, it is determined that reframe synchronization is necessary.

  Preferably, the communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within a predetermined time, and the reframe synchronization control unit is configured such that the communication state information includes a predetermined amount of traffic within the predetermined time. When the error rate within the predetermined time exceeds the threshold and the error rate within the predetermined time exceeds the predetermined number, indicating that the error rate within the predetermined time of the other radio base station exceeds the predetermined value. Therefore, it is determined that reframe synchronization is necessary.

  According to the present invention, frame synchronization can be recovered when frame synchronization cannot be achieved among a plurality of radio base stations.

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

(Configuration of radio base station synchronization control system and reframe synchronization sequence)
FIG. 1 is a diagram showing a configuration of a radio base station synchronization control system.

  FIG. 2 is a diagram showing a sequence of reframe synchronization processing in the inter-radio base station synchronization control system.

  1 and 2, the inter-radio base station synchronization control system includes one center 1 and a plurality of radio base stations CS1a to CS1e.

  The center 1 and the radio base stations CS1a to CS1e are connected by an ISDN (Integrated Service Digital Network) network 32.

  The center 1 requests communication state information from each of the radio base stations CS1a to CS1e. Details of the communication status information will be described later.

  When each of the radio base stations CS1a to CS1e receives the communication status information request, the radio base stations CS1a to CS1e notify the communication status.

  When the center 1 receives the communication state information from each of the radio base stations CS1a to CS1e, the center 1 determines whether or not each of the radio base stations CS1a to CS1e needs reframe synchronization, and determines that the reframe synchronization is necessary In response to this, a re-frame synchronization instruction is transmitted.

  The radio base station that has received the reframe synchronization instruction executes reframe synchronization.

  The request for communication information information from the center 1 to each of the radio base stations CS1a to CS1e may be omitted. In that case, communication state information is autonomously transmitted from each of the radio base stations CS1a to CS1e to the center 1 (for example, transmitted at regular intervals).

(Detailed configuration of radio base station synchronization control system)
FIG. 3 is a diagram illustrating a detailed configuration of the inter-radio base station synchronization control system. In the figure, the radio base station is represented by the configuration of the radio base station CS1a. The configurations of the other radio base stations CS1b to CS1e are the same.

  Referring to FIG. 3, the radio base station CS1a includes a GPS antenna 30, a radio antenna 31, a radio module 27, a GPS receiver 28, a radio signal processing unit 26, a radio control unit 25, and a central control unit. 22, a voice control unit 24, a line control unit 23, and a power supply unit 29.

  GPS antenna 30, radio antenna 31, radio module 27, GPS receiver 28, radio signal processing unit 26, radio control unit 25, central control unit 22, voice control unit 24, and line control unit 23 And a power supply unit 29.

  The GPS antenna 30 receives a signal defining a reference timing transmitted from a GPS artificial satellite.

  The GPS receiver 28 converts a signal defining the reference timing received by the GPS antenna 30 into a digital reference timing signal and outputs the digital reference timing signal to the radio control unit 30.

  The radio antenna 31 receives an RF (Radio Frequency) band radio signal from another radio base station or a radio terminal station, and transmits an RF band radio signal to the radio terminal station.

  The radio module 27 extracts a radio channel signal designated by a control signal (not shown) from each radio channel signal included in the RF band radio signal received by the radio antenna 31 and converts the signal to a baseband signal. . Then, the wireless module 27 converts the baseband signal that is an analog signal into reception data that is a digital signal, and outputs the received data to the wireless control unit 30. Further, the wireless module 27 converts the modulated transmission data, which is a digital signal received from the wireless signal processing unit 26, into an analog signal, amplifies the transmission signal obtained by frequency-converting the analog signal into the RF band, and supplies the signal to the wireless antenna 31. Output.

  The wireless signal processing unit 26 demodulates the reception data output from the wireless module 27 and determines whether or not each frame in the demodulated reception data has an error. The radio signal processing unit 26 modulates transmission data to be sent to the radio terminal station.

  The wireless control unit 25 includes a communication state information creation unit 21 and a frame synchronization control unit 33.

  The communication state information generation unit 21 creates communication state information based on the error determination by the wireless module 27.

  FIG. 4 is a diagram showing the contents of each item included in the communication state information.

  Referring to FIG. 4, the communication state information includes time information Ts, traffic information Fs, and error information Es.

  The time information Ts represents from what time to what time the traffic information Fs and the error information Es are from 8 o'clock to 9 o'clock.

  The traffic information Fs represents the traffic volume. A specific example of the traffic information Fs is the sum of the usage times of the used radio channels or the number of used reception slots (that is, uplink slots) within the time represented by the time information Ts. Others may be used.

  The error information Es represents the number of reception errors or the reception error rate. A specific example of the error information Es is the number of errors in the reception slot within the time represented by the time information Ts (that is, the number of reception slots in error among the used reception slots) or the error rate of the reception slot. (In other words, the ratio of reception slots with errors out of the reception slots used), but may be other.

  In the following description, the traffic information Fs is the number of used reception slots represented by the time information Ts, and the error information Es is the number of errors in the reception slots within the time represented by the time information Ts.

  A procedure for creating communication state information by the communication state information creating unit 21 will be described later.

  The frame synchronization control unit 33 synchronizes the TDMA / TDD frame of its own station with the reference timing signal output from the GPS receiver 28. The frame synchronization control unit 33 tunes its own clock to the reference clock transmitted from the center 1 in order to maintain the synchronization of the established TDMA / TDD frame.

  When receiving a re-frame synchronization instruction from the center 1, the frame synchronization control unit 33 synchronizes the TDMA / TDD frame of its own station again with the reference timing signal output from the GPS receiver 28.

  The central control unit 22 controls the operation of the entire radio base station.

  The voice control unit 24 controls voice output.

  The line control unit 23 outputs the communication status information received from the central control unit 22 to the ISDN network 32, and outputs the request for communication status information received from the ISDN network 32 and the clock synchronization signal to the central control unit 22.

  The power supply unit 29 converts an AC voltage into a DC voltage and supplies the DC voltage to each component.

  Referring again to FIG. 3, the center 1 includes a line control unit 2, a reframe synchronization control unit 3, a base station list storage unit 4, and a clock generation unit 5.

  The base station list storage unit 4 stores, for each radio base station, a base station list that defines radio base stations around it.

  The clock generator 5 generates a reference clock signal. The reference clock signal is sent to each radio base station, and the clocks are tuned in CS1a to CS1e.

  The reframe synchronization control unit 3 is configured such that the communication state information indicates that the number of used reception slots within one hour is equal to or greater than a specified value, the error rate of the reception slots within one hour exceeds the first threshold Thr1, and 1 Reframe synchronization when the error rate of the received slot in time indicates that the error rate of the other radio base station in the number of times exceeding the third threshold Thr3 is greater than the second threshold Thr2 Is deemed necessary. Detailed processing of the reframe synchronization control unit 3 will be described later.

  The line control unit 2 outputs the request for communication state information received from the reframe synchronization control unit 3 and the synchronous clock signal received from the clock generation unit 5 to the ISDN network 32 and also receives the communication state information received from the ISDN network 32. This is output to the reframe synchronization control unit 3.

(Operations for creating communication status information for wireless base stations)
FIG. 5 is a flowchart showing an operation procedure for creating communication state information of the radio base station CS1a. Each step of the flowchart is executed by reading a program from a memory (not shown). This program can be installed externally.

  Referring to FIG. 5, first, the communication state information creation unit 21 executes variable initialization. That is, the time information Ts of the communication status information is initialized to the time zone one hour before the current time, the traffic information Fs = 0 of the communication status information, the error information Es = 0 of the communication status information, and the traffic counter of the current time zone Initialization is performed to Ft = 0 (step S101).

  Next, the communication state information creation unit 21 updates the time information Ts, the traffic information Fs, and the error information Es of the communication status information at the update timing of 0 minutes per hour (YES in step S102). That is, the time information Ts of the communication state information is incremented by one hour, the value of the traffic counter Ft of the current time zone at that time is set in the traffic information Fs of the communication state information, and the error information Es of the communication state information The value of the error count Et in the current time zone at the time is set. Further, the communication information creating unit 21 resets the traffic counter Ft for the current time zone and the error counter Et for the current time zone to 0 (step S103).

  Next, when receiving the communication state information request (YES in step S104), the communication state information creating unit 21 transmits the communication state information including the time information Ts, the traffic information Fs, and the error information Es to the center 1 through the ISDN network 32. (Step S105).

  Next, the communication state information creation unit 21 updates the traffic counter Ft for the current time zone and the error counter Et for the current time zone. That is, the communication state information creating unit 21 adds the number of used reception slots that are not counted to the traffic counter Ft for the current time zone, and sets the error counter Et for the current time zone based on the error determination of the radio signal processing unit 26. The number of errors in the uncounted reception slot is added (step S106).

(Center operation)
6 and 7 are flowcharts showing the operation procedure of the center 1. Each step of the flowchart is executed by reading a program from a memory (not shown). This program can be installed externally.

  With reference to FIG. 6 and FIG. 7, the reframe synchronization control unit 3 transmits a request for communication state information to each of the radio base stations CS2a to CS2e (step S201).

  Next, the reframe synchronization control unit 3 starts an acquisition timer (step S202).

  Next, when the reframe synchronization control unit 3 receives the communication state information (YES in step S203), it determines whether or not the traffic amount (that is, the number of used reception slots) indicated by the traffic information Fs is equal to or greater than a specified value. If the value is equal to or greater than the specified value (YES in step S204), the received communication state information is stored (step S205).

  When the reframe synchronization control unit 3 has received the communication state information from all the target radio base stations (YES in step S206), the reframe synchronization control unit 3 proceeds to the processing after step S209.

  The reframe synchronization control unit 3 checks whether or not the acquisition timer has timed out when the communication state information has not been received from all the target radio base stations (NO in step S206), and the acquisition timer has timed out. Sometimes (YES in step S207), the process proceeds to step S209 and subsequent steps. When the acquisition timer has not timed out (NO in step S207), the reframe synchronization control unit 3 waits for reception of communication state information (step S208).

  Next, the reframe synchronization control unit 3 sets the base station number n to 0 (step S209).

  When the communication state information is stored for the nth base station, the reframe synchronization control unit 3 uses the traffic information Fs (the number of received slots used) and error information Es (reception slots) constituting the communication state information. Error number), Fs / Es is calculated, and the calculation result is the error rate SER (n) of the reception slot of the nth radio base station. Then, if the error rate SER (n) is equal to or lower than the predetermined first threshold value Thr1 (NO in step S210), the reframe synchronization control unit 3 does not require reframe synchronization for the nth radio base station. The process proceeds to step S218.

  If the error rate SER (n) exceeds a predetermined first threshold value Thr1 (YES in step S210), the reframe synchronization control unit 3 may perform reframe synchronization for the nth radio base station. Judge that there is, and investigate further.

  The reframe synchronization control unit 3 refers to the base station list in the base station list storage unit 4 and selects one of the radio base station groups around the nth radio base station. Assume that the selected radio base station is the xth base station. Further, the reframe synchronization control unit 3 initializes the counter C to 0 (step S211).

  When the communication state information is stored for the xth base station, the reframe synchronization control unit 3 reads the traffic information Fs and the error information Es, calculates Fs / Es, and calculates the calculation result as the xth. Error rate SER (x) of the receiving slot of the base station. If the difference between the error rate SER (n) and the error rate SER (x) is equal to or less than the predetermined second threshold Thr2 (NO in step S212), the reframe synchronization control unit 3 updates the base station list. Referring to this, it is checked whether there are other wireless base stations around the nth wireless base station. If there are no other wireless base stations (YES in step S213), the process proceeds to step S218.

  On the other hand, when there are other wireless base stations around the n-th wireless base station (NO in step S213), the reframe synchronization control unit 3 selects the surrounding wireless base station and selects the selected wireless base station Is the xth base station, and the process returns to step S212 (step S214).

  If the difference between the error rate SER (n) and the error rate SER (x) exceeds the predetermined second threshold Thr2 (YES in step S212), the reframe synchronization control unit 3 increments the counter C ( Step S215).

  Next, if the value of the counter C is equal to or smaller than the predetermined third threshold Thr3 (NO in step S216), the reframe synchronization control unit 3 refers to the base station list and determines the nth radio base station. It is checked whether there are any other wireless base stations in the surroundings. If there are no other wireless base stations (YES in step S213), the process proceeds to step S218. On the other hand, when there is another base station in the vicinity of the nth base station (NO in step S213), the reframe synchronization control unit 3 selects a surrounding radio base station, and selects the selected base station as the xth Assuming that it is the th base station, the process returns to step S212 (step S214).

  On the other hand, if the value of the counter C exceeds the predetermined third threshold Thr3 (YES in step S216), the reframe synchronization control unit 3 needs reframe synchronization for the nth radio base station. Judgment is made and a re-frame synchronization instruction is transmitted to the nth radio base station. The frame synchronization control unit 33 of the radio base station that has received the re-frame synchronization instruction again synchronizes the TDMA / TDD frame of its own station with the reference timing signal output from the GPS receiver 28 (step S217).

  Next, in step S218, the reframe synchronization control unit 3 determines that n is not final, that is, if the reframe synchronization is not necessary for all radio base stations (NO in step S218). The base station number n is incremented by 1 (step S219). On the other hand, when n is final, that is, when it is determined whether reframe synchronization is necessary for all radio base stations (YES in step S218), the reframe synchronization control unit 3 ends the reframe synchronization control. .

  As described above, according to the inter-radio base station synchronization control system according to the present embodiment, it is early detected that frame synchronization has been lost using communication information information, and reframe synchronization is performed. It is possible to return to the communication state. Further, even when the frame is out of synchronization, the service can be continuously provided as it is without interruption of the service for frame synchronization as long as the communication quality is not affected.

(Modification)
The present invention is not limited to the above embodiment. Hereinafter, modifications of the embodiment will be described.

(1) Communication state information In the embodiment of the present invention, the communication state information including information on the number of reception slots used by the radio base station and the number of errors in the reception slot is transmitted, and the reception slot is determined from the communication state information received by the center. However, the wireless base station may calculate the error rate of the reception slot and transmit communication state information including information on the number of used reception slots and the error rate of the reception slot.

(2) Judgment criteria for reframe synchronization In the embodiment of the present invention, the reframe synchronization control unit 3 indicates that the communication state information indicates that the number of used reception slots within one hour is equal to or greater than a specified value, The error rate of the reception slot exceeds the first threshold value Thr1, and the error rate of the reception slot within one hour exceeds the third threshold value Thr3. Although it has been determined that reframe synchronization is necessary when the threshold value Thr2 is greater than the threshold value Thr2, the present invention is not limited to this.

  For example, the reframe synchronization control unit 3 indicates that the communication status information indicates that the number of used reception slots within one hour is equal to or greater than a specified value, and the number of errors in the reception slots within one hour exceeds the first threshold Thr1 ′. In addition, the number of errors in the reception slot in one hour exceeds the second threshold Thr2 ′ more than the number of errors in the reception slot in one hour of other radio base stations that exceeds the third threshold Thr3 ′. , It may be determined that reframe synchronization is necessary.

  In this case, the error rate SER (n) of the reception slot within one hour of the nth radio base station in step S210 shown in FIG. ) And Thr1 is replaced with Thr1 ′.

  Also, the error rate SER (n) of the reception slot within one hour of the nth radio base station in step S212 is replaced with the error number SEN (n) of the reception slot within one hour of the nth radio base station, The error rate SER (x) of the reception slot within one hour of the xth radio base station is replaced with the error number SEN (x) of the reception slot within one hour of the xth radio base station, and Thr2 is replaced with Thr2 ′. Replaced.

  Further, Thr3 in step S216 is replaced with Thr3 ′.

(3) Frame synchronization Although the frame synchronization control unit 33 synchronizes the TDMA / TDD frame of its own station with the reference timing signal output from the GPS receiver, the present invention is not limited to this. For example, a radio signal transmitted from another radio base station may be received, and the TDMA / TDD frame of the local station may be synchronized with the TDMA / TDD frame included in the radio signal.

(4) Maintaining synchronization based on the reference clock In the embodiment of the present invention, the frame synchronization control unit 33 uses the reference clock transmitted from the center 1 as the reference clock transmitted from the center 1 in order to maintain the synchronization of the established TDMA / TDD frame. Although the clock is tuned, such clock tuning is not necessarily required, and such clock tuning may not be performed.

  The embodiment disclosed this time 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.

It is a figure which shows the structure of the synchronous control system between radio base stations. It is a figure showing the sequence of the re-frame synchronization process of the synchronous control system between radio base stations. It is a figure which shows the detailed structure of the synchronous control system between radio base stations. It is a figure showing the content of each item contained in communication status information. It is a flowchart which shows the operation | movement procedure of communication state information preparation of radio base station CS1a. 3 is a flowchart showing an operation procedure of the center 1. 3 is a flowchart showing an operation procedure of the center 1. It is a figure for demonstrating a TDMA / TDD system. It is a figure showing the state by which the frame synchronization was established in the radio base stations A, B, and C. FIG. 7 is a diagram illustrating a state in which frame synchronization cannot be achieved at a radio base station B.

Explanation of symbols

  1 center, 3 reframe synchronization control unit, 4 base station list storage unit, CS1a to CS1e radio base station, 21 communication state information creation unit, 22 central control unit, 2, 23 line control unit, 24 voice control unit, 25 radio Control unit, 26 Wireless signal processing unit, 27 Wireless module, 28 GPS receiver, 29 Power supply unit, 30 GPS antenna, 31 Wireless antenna, 32 ISDN network, 33 Frame synchronization control unit

Claims (8)

A frame synchronization unit that synchronizes the frame of the local station with the reference signal from the GPS antenna or the frame of another radio base station;
A communication state information creating unit for creating communication state information representing the communication state of the own station;
A communication unit for transmitting the communication state information to the inter-radio base station synchronization control center and receiving a reframe synchronization instruction from the inter-radio base station synchronization control center;
The frame synchronization unit is a radio base station that, when receiving a reframe synchronization instruction from the inter-radio base station synchronization control center, synchronizes the frame of the own station again.   The radio base station according to claim 1, wherein the communication state information creating unit creates communication state information representing a traffic amount within a predetermined time and an error count or an error rate within the predetermined time. A radio base station synchronization control center for controlling frame synchronization between a plurality of radio base stations,
A communication unit that receives communication state information representing a communication state of the radio base station from each radio base station;
A reframe synchronization control unit that determines whether each radio base station needs reframe synchronization based on the received communication state information of each radio base station;
The inter-radio base station synchronization control center, wherein the communication unit transmits a re-frame synchronization instruction to a radio base station that is determined to require the re-frame synchronization. The communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within the predetermined time,
The reframe synchronization control unit is configured so that the communication status information indicates that the traffic amount within a predetermined time is equal to or greater than a predetermined value, the number of errors within the predetermined time exceeds a threshold, and the number of errors within the predetermined time is a predetermined number. 4. The inter-radio base station synchronization control center according to claim 3, wherein it is determined that reframe synchronization is necessary when it indicates that the number of errors exceeding a predetermined value exceeds the number of errors within the predetermined time of other radio base stations. The communication state information includes a traffic amount within a predetermined time and the number of errors or an error rate within the predetermined time,
The reframe synchronization control unit is configured so that the communication state information indicates that a traffic amount within a predetermined time is equal to or greater than a predetermined value, an error rate within the predetermined time exceeds a threshold, and an error rate within the predetermined time is a predetermined number. 4. The inter-radio base station synchronization control center according to claim 3, wherein it is determined that reframe synchronization is necessary when it indicates that the error rate within the predetermined time of the other radio base stations exceeds the predetermined value. A synchronization control method for a radio base station synchronization control system comprising a plurality of radio base stations and a radio base station synchronization control center for controlling frame synchronization between the plurality of radio base stations,
Each radio base station synchronizes its own frame with a reference signal from a GPS antenna or a frame of another radio base station;
Each wireless base station creates communication state information for creating communication state information representing the communication state of the own station;
Each radio base station transmitting the communication state information to a radio base station synchronization control center;
The inter-radio base station synchronization control center receiving communication state information representing a communication state of the radio base station from each radio base station;
A reframe synchronization control step in which the radio base station synchronization control center determines whether or not each radio base station needs reframe synchronization based on the received communication state information of each radio base station;
The radio base station synchronization control center transmits a reframe synchronization instruction to the radio base station determined to require the reframe synchronization;
When each radio base station receives a reframe synchronization instruction from the inter-radio base station synchronization control center, it again synchronizes its own frame with the reference signal from the GPS antenna or the frame of another radio base station. A synchronization control method for an inter-radio base station synchronization control system. In the communication status information creation step, each of the radio base stations creates communication status information indicating a traffic amount within a predetermined time and the number of errors or an error rate within the predetermined time,
In the reframe synchronization control step, the inter-radio base station synchronization control center is configured such that the communication state information indicates that the traffic amount within the predetermined time is equal to or greater than a predetermined value, the number of errors within the predetermined time exceeds a threshold value, and The re-frame synchronization is determined to be necessary when the number of errors within the predetermined time indicates that the number of errors exceeding the predetermined number exceeds the number of errors within the predetermined time exceeding a predetermined value. 6. A synchronization control method for an inter-radio base station synchronization control system according to 6. In the communication status information creating step, each of the radio base stations creates communication status information indicating a traffic amount within a predetermined time and the number of errors or an error rate within the predetermined time,
In the reframe synchronization control step, the inter-radio base station synchronization control center is configured such that the communication state information indicates that the traffic amount within the predetermined time is equal to or greater than a predetermined value, the error rate within the predetermined time exceeds a threshold value, and The re-frame synchronization is determined to be necessary when the error rate within the predetermined time indicates that the error rate within the predetermined time of another radio base station exceeding a predetermined number exceeds a predetermined value. 6. A synchronization control method for an inter-radio base station synchronization control system according to 6.

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