JP2014239271A - Base station and transmission timing determination method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station and a transmission timing determination method therefor, capable of operating without producing a trouble such as interference even if a GPS mounting base station halts.SOLUTION: The transmission timing determination method for the base station 110, performing communication with a radio terminal 104 and frame synchronization with other base stations, includes: acquiring a control signal of the plurality of other base stations existent in the periphery of the base station; calculating an average value of the reception timing of the acquired control signal; excluding the reception timing of another base station having a largest difference from the average value of the reception timing; and repeating the average value calculation of the reception timing and the exclusion of the reception timing of the other base station having the largest difference, so as to determine the average value of the reception timing, having a standard deviation smaller than and including a predetermined value, to be the transmission timing of the self-station.

Description

  The present invention relates to a base station that performs communication with a wireless terminal and frame synchronization with another base station, and a transmission timing determination method thereof.

  In the PHS, a base station serving as a synchronization absolute reference is equipped with a GPS unit, and a base station equipped with a GPS unit (hereinafter referred to as a GPS-equipped base station) receives a clock signal (1PPS ( The transmission / reception timing synchronization (GPS synchronization) is performed using the phase of (Pulse Per Second) signal) as an absolute reference (for example, Patent Document 1). Thereby, high synchronization accuracy is obtained between base stations, and the transmission / reception timings of the base stations can be matched. For this reason, although it is desirable to mount a GPS unit in all the base stations, it may be difficult in terms of cost. Therefore, in a base station not equipped with a GPS unit (hereinafter referred to as a non-mounted base station), synchronization between base stations (hereinafter referred to as frame synchronization) is performed by receiving a control channel transmitted by a surrounding GPS mounted base station. ) To synchronize transmission / reception timing.

JP 2001-339373 A

  As described above, the non-mounted base station can maintain the accuracy of the transmission timing by synchronizing with the GPS mounted base station. However, when a disaster such as an earthquake occurs, the GPS-equipped base station may stop due to a power failure. In such a case, the non-equipped base station cannot perform frame synchronization with the GPS-equipped base station, that is, operates non-synchronously, causing interference due to a decrease in synchronization accuracy. Further, if the operation of the non-equipped base station is stopped until the GPS-equipped base station is restored in order to avoid the occurrence of interference, an area where communication is impossible occurs in the area.

  In view of such problems, the present invention provides a base station that can be operated without causing problems such as interference even when a GPS-equipped base station is stopped, and a transmission timing determination method thereof The purpose is to do.

  In order to solve the above problems, a representative configuration of a base station transmission timing determination method according to the present invention is a base station transmission timing determination method for performing communication with a wireless terminal and frame synchronization with another base station. The control signal of a plurality of other base stations existing around the base station is acquired, the average value of the received timings of the acquired control signals is calculated, and the difference from the average value of the reception timing is the largest Reception timing when the standard deviation is less than or equal to the predetermined value by repeating the calculation of the average value of the reception timing and the exclusion of the reception timing of the other base station with the largest difference, excluding the reception timing of other base stations Is the transmission timing of the local station.

  It is preferable to perform the above processing when a control signal from a GPS-equipped base station cannot be received. Or when the magnitude | size of an earthquake is more than predetermined value, it is preferable to perform said process. This is because if the magnitude of the earthquake is large, the GPS-equipped base station is likely to stop.

  In order to solve the above problems, a typical configuration of a base station according to the present invention is a base station that performs communication with a wireless terminal and frame synchronization with another base station, and is provided around the base station. The wireless communication unit that acquires the control signals of a plurality of other base stations that exist and the average value of the reception timings of the acquired control signals are calculated, and the reception of the other base station that has the largest difference from the average value of the reception timings And a timing determination unit that determines the average value of the reception timings when the standard deviation is equal to or less than a predetermined value by excluding the timings and repeating them, and the transmission timing of the own station.

  ADVANTAGE OF THE INVENTION According to this invention, even when a GPS mounting base station stops, the base station which can be operate | used without producing malfunctions, such as interference, and its transmission timing determination method can be provided.

It is a figure explaining the communication system containing the base station concerning 1st Embodiment. It is a functional block diagram which illustrates the composition of the base station concerning a 1st embodiment. It is a flowchart explaining the transmission timing determination method of the base station concerning 1st Embodiment. It is the figure which illustrated calculation of an average value and a difference with it. It is a functional block diagram which illustrates the composition of the base station concerning a 2nd embodiment. It is a flowchart explaining the transmission timing determination method of the base station concerning 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(First embodiment)
FIG. 1 is a diagram illustrating a communication system 100 including a base station 110 according to the first embodiment. FIG. 2 is a functional block diagram illustrating the configuration of the base station 110 according to the first embodiment. Hereinafter, the base station 110 and the synchronization method thereof according to the first embodiment will be described with reference to the communication system 100 shown in FIG.

  As shown in FIG. 1, in the communication system 100, a plurality of base stations 110a, 110b, 110c, 110d, 110e, and 110f are installed in an area 100a. The base stations 110a to 110f perform wireless communication with the wireless terminal 104 (see FIG. 2). The base station 110 a is a GPS-equipped base station on which a GPS unit (not shown) is mounted, and performs GPS synchronization by receiving a clock signal from the GPS satellite 102.

  On the other hand, the base stations 110b to 110f are non-mounted base stations not equipped with a GPS unit, and receive frame control by receiving control signals from the base station 110a (another base station) that is a GPS-equipped base station. Is going. Since base stations 110b to 110f all have the same configuration, base stations 110b to 110f are referred to as base stations 110 in the following description unless otherwise specified.

  As shown in FIG. 2, the base station 110 includes a control unit 112. The control unit 112 manages and controls the entire base station 110 by a semiconductor integrated circuit including a central processing unit (CPU). As will be described later, in this embodiment, the control unit 112 also functions as the timing determination unit 114.

  The radio communication unit 120 performs radio communication with the radio terminal 104 such as a PHS terminal via the communication antenna 120a and frame synchronization with other base stations 110 (the base station 110c is illustrated in FIG. 2) existing in the vicinity. Do. The control channel of another base station 110c acquired by communication by the wireless communication unit 132 is controlled via the baseband unit 122 that performs analog / digital conversion of the baseband signal and performs processing such as frame synchronization and channel decoding. Is transmitted to the unit 112.

  FIG. 3 is a flowchart for explaining a transmission timing determination method of the base station 110 according to the first embodiment. Hereinafter, the operation of the control unit 112 as the timing determination unit 114 will be described with reference to FIG. As shown in FIG. 3, in the transmission timing determination method of the base station 110 according to the first embodiment, first, the control unit 112 can receive a control signal from the base station 110a that is a GPS-equipped base station in the wireless communication unit 120. It is determined whether or not (step S202). The fact that the control signal from the base station 110a can be received (YES in step S202) means that the base station 110a is operating, so the control unit 112 is synchronized with the base station 110a (frame synchronization). ) Is maintained (step S204).

  On the other hand, when the control signal from the base station 110a cannot be received (NO in step S202), the control unit 112 determines whether or not the own station is communicating with the wireless terminal 104 (during call connection). (Step S206). When the communication is in progress (YES in step S206), the control unit 112 maintains the connection state (operation state) between the local station and the wireless terminal 104, and waits until the communication with the wireless terminal 104 ends. When the own station is not communicating with the wireless terminal 104 or when the communication with the wireless terminal 104 is finished (NO in step S206), the control unit 112 stops the own station (OUT: Out of Service). Then, the wireless communication unit 120 performs a base station search for acquiring control signals of other base stations 110 existing around the own station (step S208).

  When the control signal of another base station 110 (non-equipped base station other than the own station) is acquired by the base station search, the timing determination unit 114 calculates the average value of the reception timing of the acquired control signal, The difference from the acquired control signal is calculated (step S210). FIG. 4 is a diagram illustrating the calculation of the average value and the difference between the average value. FIG. 4 illustrates a case where the base station 110b receives control signals from the base stations 110c to 110f, which are surrounding base stations.

  As shown in FIG. 4, the base station 110b receives control signals transmitted from the base stations 110c to 110f. Specifically, the base station 110c transmits a control signal at timing 4, the base station 110d at timing 6, the base station 110e at timing 10, and the base station 110f at timing 4. In step S210, the timing determination unit 114 first calculates an average value of these reception timings. In the example shown in FIG. 4, the average value is 6.

  Next, the timing determination unit 114 calculates a difference (deviation) between the reception timing of each of the base stations 110c to 110f and the average value, and excludes reception timings of other base stations having the largest difference from the average value (step) S212). In the example of FIG. 4, the reception timing of the base station 110e having the largest difference from the average value 6 is excluded. Thereafter, the timing determination unit 114 calculates the standard deviation after the exclusion, and determines whether or not the standard deviation is a predetermined value or less (step S214).

  When the standard deviation is not less than the predetermined value (NO in step S214), the timing determination unit 114 repeats steps S210 to S212. In the example of FIG. 4, after excluding the reception timing of the base station 110e, the average value of the reception timings of the base stations 110c, 110d, and 110f and the difference between the reception timing and each reception timing are calculated (step S210). At this time, since the average value is 4.67, the reception timing of the base station 110d having the largest difference is excluded (step S212).

  Thereafter, the timing determination unit 114 calculates again the standard deviation after exclusion, and determines whether the standard deviation is equal to or less than a predetermined value. In the example of FIG. 4, since the reception timings of the base stations 110c and 110f remaining after the exclusion are 4, the standard deviation is 0. Therefore, the timing determination unit 114 determines that the standard deviation has become equal to or less than the predetermined value, and determines the reception timing at that time, that is, the reception timing 4 as the transmission timing of the local station (step S216). In the present embodiment, the case where it is determined that the standard deviation is 0 or less is exemplified, but the present invention is not limited to this. The predetermined value may be a value other than 0, and can be set as appropriate.

  As described above, according to the base station 110 according to the first embodiment, when it becomes impossible to perform frame synchronization with the GPS-equipped base station, surrounding non-mounted bases that are not equipped with GPS. The transmission timing of the own station is determined in accordance with the reception timing of the control signal of the station, that is, the transmission timing of the control signal of the surrounding non-mounted base station. Thereby, even when the GPS-equipped base station is stopped, it becomes possible to operate the non-equipped base station without causing interference.

(Second Embodiment)
FIG. 5 is a functional block diagram illustrating the configuration of the base station 200 according to the second embodiment. FIG. 6 is a flowchart for explaining a transmission timing determination method of the base station 200 according to the second embodiment. In addition, in the base station 200 of 2nd Embodiment and its transmission timing determination method, about the component and operation | movement which overlap with 1st Embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 5, the base station 200 of the second embodiment further includes an earthquake detection unit 124 in addition to the components of the communication system 100 of the first embodiment. Thereby, in the transmission timing determination method of the base station 200, as shown in FIG. 6, the earthquake detection unit 124 monitors whether or not an earthquake has occurred (step S220). Until the earthquake occurs (NO in step S220), since the base station 110a that is a GPS-equipped base station is normally operated, the control unit 112 maintains synchronization (frame synchronization) with the base station 110a (step synchronization). S204).

  On the other hand, if an earthquake occurs (YES in step S220), the control unit 112 determines the magnitude of the earthquake (step S222), and if the scale does not cause the base station 110a to stop due to a power failure (less than a predetermined value). (NO in step S222), synchronization with the base station 110a is maintained (step S204). If the scale is such that the base station 110a can be stopped due to a power failure (YES in step S222), the control unit 112 performs the processing from step S206 onward in the same manner as the base station 110 of the first embodiment. By performing processing according to the magnitude of the earthquake in this way, even when a GPS-equipped base station stops during a disaster, it is possible to operate a non-equipped base station without causing interference, It is possible to secure a lifeline.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a base station that performs communication with a wireless terminal and frame synchronization with another base station, and a transmission timing determination method thereof.

DESCRIPTION OF SYMBOLS 100 ... Communication system, 100a ... Area, 102 ... GPS satellite, 104 ... Wireless terminal, 110 ... Base station, 110a ... Base station, 110b ... Base station, 110c ... Base station, 110d ... Base station, 110e ... Base station, 110f ... base station, 112 ... control unit, 114 ... timing determination unit, 120 ... wireless communication unit, 120a ... communication antenna, 122 ... baseband unit, 124 ... earthquake detection unit, 200 ... base station

Claims (4)

A transmission timing determination method of a base station that performs communication with a wireless terminal and performs frame synchronization with another base station,
Acquire control signals of a plurality of other base stations existing around the base station,
Calculate the average value of the reception timing of the acquired control signal,
Exclude reception timings of other base stations having the largest difference from the average value of the reception timings,
By repeating the calculation of the average value of the reception timing and the exclusion of the reception timing of the other base station having the largest difference, the average value of the reception timing when the standard deviation is equal to or smaller than a predetermined value is determined as the transmission timing of the local station. A base station transmission timing determination method characterized by:   The base station transmission timing determination method according to claim 1, wherein the processing is performed when a control signal from a GPS-equipped base station cannot be received.   The base station transmission timing determination method according to claim 1, wherein the processing is performed when the magnitude of the earthquake is equal to or greater than a predetermined value. A base station that performs communication with a wireless terminal and frame synchronization with another base station,
A wireless communication unit for acquiring control signals of a plurality of other base stations existing around the base station;
The average value of the reception timing of the acquired control signal is calculated, the reception timing of the other base station having the largest difference from the average value of the reception timing is excluded, and the standard deviation is less than or equal to a predetermined value by repeating them A timing determination unit that determines the average value of the reception timing when it becomes the transmission timing of its own station,
A base station comprising:

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