JP2005136748A - Mobile communication system, mobile apparatus and base station apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To search a synchronization signal in a mobile communication system in a proper time range. <P>SOLUTION: In a base station apparatus 20, a GPS signal synchronizing state detecting part 30 detects and announces at least either the synchronizing state of an in-base station time information and a GPS signal or the receiving state of the GPS signal as a synchronizing state signal, thus the synchronizing signal announced by the base station apparatus 20 can be searched in the time range based on the synchronizing state signal. Consequently, in the mobile communication system, cell search characteristics and hand over characteristics are increased in speeds in cell searching and hand-over, processing is reduced in a hand over time and power consumption is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mobile communication system, a mobile station apparatus, and a base station apparatus, and more particularly to speeding up these communication processes.

  In a mobile communication system that generally employs a synchronous CDMA (Code Division Multiple Access) system, a base station that communicates with a mobile station such as a mobile phone is a GPS that constitutes a GPS (Global Positioning System). Receives a signal (GPS signal) indicating standard time (UTC: Universal Time Coordinated) from the satellite, generates base station time information and frequency synchronized with the received GPS signal, and synchronizes with the base station time information and frequency. Performs processing related to wireless communication.

  Therefore, strict management is required for the time information in the base station, and various regulations are also made in the standard. In addition, regarding the timing (transmission timing) for transmitting a signal from the base station, which is controlled based on the time information in the base station, cell search for searching for a base station with which the mobile station can communicate, and communication between the mobile station and the base station Since it is closely related to the characteristics related to communication processing such as handover for switching, adding and deleting lines, it is strictly defined. Therefore, for example, a relatively easy cell search shown in Patent Document 1 as a conventional example is possible.

In such a communication system, a mobile station is a PN code (Pseudorandom).
The PN code offset information of the pilot signal necessary for receiving the pilot signal such as (Noise code) is broadcast. When performing a cell search or a handover, the mobile station searches for and detects a pilot signal based on offset information broadcast from the base station. Therefore, in order to speed up the communication process, a technique is required for the mobile station to quickly detect the pilot signal.

However, if there is a problem with the synchronization state between the time information in the base station and the GPS signal due to the reason that the GPS signal cannot be received at the base station, a time lag (error) in the transmission timing of the base station Therefore, in the conventional communication system, for all base stations, pilots are used in a time range assuming the maximum transmission timing error allowed for establishing synchronization between the mobile station and the base station. A signal search was being performed.
JP-A-9-261711

  In the conventional communication system, for example, when the synchronization state between the time information in the base station and the GPS signal is maintained, the pilot signal is searched unnecessarily in a wide time range. Speeding up of cell search (pilot signal search) characteristics and handover characteristics is hindered, and power consumption is also increased.

  In view of the above points, one of the objects of the present invention is to notify the synchronization state in the base station, thereby speeding up the cell search characteristics and speeding up the handover characteristics, and further reducing the processing at the time of handover. An object of the present invention is to provide a mobile communication system, a mobile station apparatus, and a base station apparatus that can reduce power consumption.

  A communication system according to the present invention is a communication system having a base station apparatus and a mobile station apparatus that transmit and receive signals to each other, and the base station apparatus transmits signals to the mobile station apparatus based on base station time information. Means for controlling the transmission timing of the base station, means for detecting at least one of the synchronization state of the time information in the base station and the GPS signal or the reception state of the GPS signal as a synchronization state signal, and the synchronization state signal as the mobile station device or Means for notifying at least one of the other base station apparatuses, and the mobile station apparatus, based on the synchronization state signal received from the base station apparatus, transmits a predetermined synchronization signal notified by the base station apparatus. A time range setting means for setting a time range to be searched; and a time range set by the time range setting means, wherein the synchronization signal is obtained from a signal received from the base station apparatus. And a means to search.

  A mobile station apparatus according to the present invention is a mobile station apparatus that transmits and receives a signal to and from a base station apparatus, and the synchronization state between the base station time information received from the base station apparatus and the GPS signal or the GPS signal Based on a synchronization state signal including information indicating at least one of reception states, a time range setting unit that sets a time range for searching for a predetermined synchronization signal broadcast by the base station apparatus, and the time range setting unit sets Means for searching for the synchronization signal from the signal received from the base station apparatus within a predetermined time range.

  A base station apparatus according to the present invention is a base station apparatus that transmits / receives a signal to / from a mobile station apparatus, and controls a transmission timing of a signal to the mobile station apparatus based on time information in the base station; Means for detecting at least one of a synchronization state between the time information in the base station and the GPS signal or a reception state of the GPS signal as a synchronization state signal, and at least one of the mobile station device or another base station device. Means for informing the user.

  In another preferable aspect of the base station apparatus according to the present invention, the synchronization state signal includes information indicating whether or not the GPS signal is received in the base station apparatus.

  In still another preferred aspect of the base station apparatus according to the present invention, the synchronization state signal includes information indicating an elapsed time since the GPS signal was last received at the base station apparatus.

  According to the present invention, mobile communication that realizes speeding up of cell search characteristics and speeding up of handover characteristics, and further reduction of processing and power consumption at the time of handover by informing the synchronization state in the base station, etc. A system, a mobile station apparatus, and a base station apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of a communication system (hereinafter, this communication system) according to an example of an embodiment of the present invention.

  This communication system performs wired communication with base stations B1, B2, and B3 that are geographically separated, a mobile station M that wirelessly transmits and receives signals to and from the base stations B1, B2, and B3. And a control station C that controls them. The mobile station M exists in an area A1 (area indicated by a circle centered on the base station B1) that can communicate with the base station B1, and communicates with the base station B1. Hereinafter, the base stations B1, B2, and B3 are simply referred to as the base station B when it is not necessary to distinguish them.

  2 and 3 are block diagrams showing schematic configurations of the base station device 20 as the base station B and the mobile station device 40 as the mobile station M, respectively.

  First, the base station apparatus 20 will be described. The base station apparatus 20 includes a GPS signal processing unit 26, a GPS signal synchronization state detection unit 30, a line interface unit 25, a transmission / reception processing unit 24, and an RF (Radio Frequency) processing unit 23.

  The GPS signal processing unit 26 controls signal transmission timing from the base station apparatus 20 to the mobile station apparatus 40 based on the base station time information. For example, the GPS signal processing unit 26 receives a GPS signal arriving at the antenna 22 and controls transmission timing based on the received GPS signal. That is, the GPS signal processing unit 26 generates base station time information synchronized with the GPS signal as time information in the base station apparatus 20, and controls transmission timing based on the base station time information. In this way, for example, communication processes such as base station time information and transmission timing can be synchronized between different base station apparatuses 20.

  The GPS signal synchronization state detection unit 30 detects at least one of the synchronization state between the base station time information and the GPS signal or the reception state of the GPS signal as a synchronization state signal. For example, the GPS signal reception detection unit 31 of the GPS signal synchronization state detection unit 30 detects whether or not a GPS signal is received by the GPS signal processing unit 26. In this case, the synchronization state signal includes information indicating whether or not the GPS signal is received by the base station apparatus 20. The synchronization state signal is output from the GPS signal synchronization state detection unit 30 to the line interface unit 25.

  The line interface unit 25 wire-transmits the synchronization state signal received from the GPS signal synchronization state detection unit 30 to a control station device (not shown) as the control station C. Further, the line interface unit 25 outputs the synchronization state signal to the transmission / reception processing unit 24 when wirelessly transmitting the synchronization state signal. In addition, the control station apparatus that has received the synchronization state signal from the base station apparatus 20 transmits the synchronization state signal to another base station apparatus 20 by wire.

  The transmission / reception processing unit 24 performs transmission processing such as channel coding or spreading processing using a spreading code on the transmission baseband signal received from the line interface unit 25 and outputs the transmission processing to the RF processing unit 23. In addition, the transmission / reception processing unit 24 performs reception processing such as despreading processing and channel decoding using the spreading code used on the transmission side for the baseband signal received from the RF processing unit 23, and the line interface unit 25. Output to.

  The RF processing unit 23 performs modulation processing for wireless transmission on the baseband signal received from the transmission / reception processing unit 24 and transmits it from the antenna 21. Further, the RF processing unit 23 performs demodulation processing and the like on the radio signal received via the antenna 21 and outputs the result to the transmission / reception processing unit 24 as a baseband signal.

  The synchronization state signal detected by the GPS signal synchronization state detection unit 30 in this way is embedded in, for example, a broadcast channel of a transmission signal, and transmitted from the base station device 20 to the mobile station device 40 or another base station device 20. At least one of them is notified, and the other base station apparatus 20 notifies this synchronization state signal in the communicable area by wireless transmission.

  Next, the mobile station apparatus 40 will be described. The mobile station device 40 includes an RF processing unit 42, a transmission / reception processing unit 43, and a control unit 50.

  The RF processing unit 42 performs demodulation processing and the like on the radio signal received via the antenna 41 and outputs the result to the transmission / reception processing unit 43 as a baseband signal. Further, the RF processing unit 42 performs modulation processing for wireless transmission on the baseband signal received from the transmission / reception processing unit 43 and transmits it from the antenna 41.

  The transmission / reception processing unit 43 performs reception processing such as despreading processing and channel decoding on the baseband signal received from the RF processing unit 42 and outputs the result to the control unit 50. Further, the transmission / reception processing unit 43 performs transmission processing such as channel coding and spreading processing on the transmission baseband signal received from the control unit 50 and outputs the transmission processing to the RF processing unit 42.

  The control unit 50 inputs and outputs baseband signals to and from the transmission / reception processing unit 43 and controls processing in the transmission / reception processing unit 43.

  For example, the time range setting unit 51 of the control unit 50 searches the time range for searching for a predetermined synchronization signal such as a pilot signal broadcast by the base station device 20 based on the synchronization state signal received from the base station device 20. Set as a range. For example, when the synchronization state signal includes information indicating whether or not the GPS signal is received in the base station device 20, the time range setting unit 51 sets the search time range based on whether or not the GPS signal is received.

  In this case, for example, the time range setting unit 51 sets a search time range in accordance with whether or not the GPS signal is received in the base station device 20. An example of this case is shown in FIG. FIG. 4 shows the relationship between the temporal position of the pilot signal broadcasted by the base station apparatus 20 as the PN code and the search time range set by the time range setting unit 51 (the time range of the PN code of the pilot signal to be searched). It is explanatory drawing. That is, PN (k) is the temporal position of the kth pilot signal in the period of the PN code, and the PN code offset position of the pilot signal (the temporal position indicated by the PN code offset information of the pilot signal). Show. The search time range D is a search time range in consideration of a propagation delay time based on the geographical distance between the mobile station device 40 and the base station device 20.

  In the example shown in FIG. 4, when the time range setting unit 51 receives information indicating that a GPS signal is received in the base station device 20, the time range setting unit 51 calculates the time information in the base station and the GPS signal. Search time range X based on an allowable transmission timing error allowed when synchronization is maintained (synchronization held state) (for example, a time range corresponding to an allowable transmission timing error in the synchronization hold state is set as search time range D Time range). When the time range setting unit 51 receives information indicating that the GPS signal is not received, the time range setting unit 51 permits transmission when the synchronization between the time information in the base station and the GPS signal is not maintained (asynchronous state). Based on the timing error, a search time range Y larger than the search time range X (for example, a time range obtained by adding a time range corresponding to the allowable transmission timing error in the asynchronous state to the search time range D or the search time range X) is set. .

  As described above, the time range setting unit 51 sets a search time range based on the synchronization state signal received from the base station apparatus 20, and searches for a signal including information indicating the search time range in the transmission / reception processing unit 43. To the unit 44.

  The synchronization signal search unit 44 searches for a synchronization signal received from the base station apparatus 20 in the search time range set by the time range setting unit 51. That is, the synchronization signal search unit 44 searches for a synchronization signal in the search time range specified by the time range setting unit 51. For example, the synchronization signal search unit 44 searches for a synchronization signal in a search time range corresponding to the presence or absence of reception of a GPS signal in the base station device 20. In this case, for example, as described above, a synchronization signal such as a pilot signal is searched for from the signal broadcast by the base station apparatus 20 in the search time range X or the search time range Y shown in FIG. Here, for example, if the search time range X is smaller than the search time range Y, the synchronization signal search unit 44, when the base station device 20 is in the synchronization holding state, has a synchronization signal in a smaller time range than in the asynchronous state. Can be explored. That is, when the GPS signal is received at the base station apparatus 20, the time required for searching for the synchronization signal is shortened compared to when the GPS signal is not received.

  Next, an example of a handover addition process when the mobile station M in the communication system (see FIG. 1) moves from the area A1 to the area A2 that can communicate with the base station B2 will be described with reference to FIG. . FIG. 5 is a flowchart showing main processing performed in the mobile station M in this case.

  The base station B transmits a synchronization state signal including information indicating whether or not the GPS signal is received by the GPS signal processing unit 26 together with identification information (information for identifying each base station B) of the mobile station. M or at least one of the other base stations B is notified, and the mobile station M receives this synchronization state signal (S110). That is, for example, the base stations B2 and B3 wire-transmit the synchronization state signal to the control station C, the control station C wire-transmits the synchronization state signal to the base station B1, and the base station B1 receives the synchronization signal received from the control station C. A status signal is reported in area A1, and mobile station M existing in area A1 receives a synchronization status signal related to base stations B2 and B3 reported from base station B1.

  Next, the time range setting unit 51 determines whether or not the GPS signals are received at the base stations B2 and B3 based on the information included in the synchronization state signal (S120). For example, in the example shown in FIG. 4 described above, the time range setting unit 51 sets the time range X when receiving information indicating that the base stations B2 and B3 are receiving GPS signals ( (S130) When information indicating that it has not been received is received, a time range Y larger than the time range X (S140) is set as the search time range for each of the base stations B2 and B3.

  Next, the synchronization signal search unit 44 searches for a synchronization signal broadcast from the base stations B2 and B3 within the search time range set by the time range setting unit 51 (S150). Then, it is further determined whether or not a synchronization signal is detected (S160), and if no synchronization signal is detected from any of the base stations B2 and B3, the search for the synchronization signal is performed again (S150), one or more synchronization signals, For example, if both synchronization signals from the base stations B2 and B3 are detected, then the reception level is determined for each synchronization signal (S170).

  If it is determined that the reception level is lower than the predetermined value for both the synchronization signals of the base stations B2 and B3, the search for the synchronization signal is performed again (S150), one or more synchronization signals, for example, the synchronization signal of the base station B2 If it is determined that only a reception level equal to or higher than a predetermined value (for example, a preset reception intensity of a pilot signal), a handover addition process is performed (S180).

  In the handover addition process, the mobile station M transmits a signal requesting the control station C to add a handover with the base station B2 (start of a new communication with the base station B2) via the base station B1. The control station C transmits the same signal related to communication with the mobile station M to both the base station B1 and the base station B2. The mobile station M receives the signals transmitted from the base station B2 in addition to the signals transmitted from the base station B1, combines these signals (addition of reception processing), and base stations B1 and B2 Start communicating with both.

  In addition to the GPS signal reception detection unit 31, the GPS signal synchronization state detection unit 30 of the base station device 20 detects an elapsed time since the last GPS signal was received at the base station device 20. Also good. FIG. 6 shows a schematic configuration of the base station apparatus 20 in this case as a block diagram.

  As shown in FIG. 6, the elapsed time detection unit 32 of the GPS signal synchronization state detection unit 30 includes a synchronization state signal including information indicating a time elapsed since the GPS signal was last received in the GPS signal processing unit 26. And a synchronization state signal including information indicating the elapsed time is notified to at least one of the mobile station device 40 or another base station device 20.

  In this case, for example, the time range setting unit 51 of the mobile station device 40 sets a search time range corresponding to information indicating the elapsed time included in the synchronization state signal received from the base station device 20. An example of this case is shown in FIG. FIG. 7 is an explanatory diagram showing the relationship between the temporal position of the pilot signal broadcasted by the base station apparatus 20 as a PN code and the search time range set by the time range setting unit 51, as in FIG. k) The search time range D and the search time range X are the same as those in FIG.

  In the example illustrated in FIG. 7, the time range setting unit 51 sets a search time range corresponding to the amount of elapsed time indicated by the synchronization state signal. In this case, for example, the time range setting unit 51 refers to a data table stored in advance in the base station apparatus 20 in association with the elapsed time magnitude T and the time range L, as shown in FIG. To set the search time range. That is, when the synchronization state signal also includes information indicating whether or not the GPS signal is received in the base station apparatus 20, the time range setting unit 51 searches if receiving information indicating that the GPS signal is received. If the time range X is set and information indicating that no GPS signal is received is received, the size of the elapsed time is determined. Then, the time range setting unit 51 reads and sets the search time range L corresponding to the magnitude of the elapsed time T from the data table shown in FIG. That is, L1 is set as the search time range if the elapsed time T is less than T1, L2 is set if it is T1 or more and less than T2, and L3 is set if it is T2 or more. Here, if the size of the search time range is gradually increased from X to L1, L2, and L3, the time range setting unit 51 can increase the search time range and decrease the elapsed time if the elapsed time is large. Thus, the search time can be set to be small.

  In this case, the synchronization signal search unit 44 searches for the synchronization signal in a time range corresponding to the amount of elapsed time indicated by the synchronization state signal. That is, in the example shown in FIG. 7, for example, the synchronization signal search unit 44 searches for a synchronization signal in a smaller time range as the elapsed time is smaller, and in a larger time range as the elapsed time is larger. In this case, the time required for searching for the synchronization signal can be shortened.

  Next, in this case, FIG. 9 is used for an example of a handover addition process when the mobile station M in the communication system (see FIG. 1) moves from the area A1 to the area A2 that can communicate with the base station B2. I will explain. FIG. 9 is a flowchart showing the main processing performed in the mobile station M in this case, as in FIG.

  The base station B obtains information indicating the presence / absence of reception of the GPS signal detected by the GPS signal reception detection unit 31, and the elapsed time since the last reception of the GPS signal detected by the elapsed time detection unit 32. The synchronization state signal including at least one of the information shown is notified to at least one of the mobile station M or another base station B together with the identification information of the own station, and the mobile station M transmits the synchronization state signal as in the case of FIG. Receive (S210). That is, for example, the base stations B2 and B3 wire-transmit the synchronization state signal to the control station C, the control station C wire-transmits the synchronization state signal to the base station B1, and the base station B1 receives the synchronization signal received from the control station C. A status signal is reported in area A1, and mobile station M existing in area A1 receives a synchronization status signal related to base stations B2 and B3 reported from base station B1.

  Based on the synchronization state signal received from the base station B1, the time range setting unit 51 of the mobile station M first determines whether or not a GPS signal is received at the base stations B2 and B3 (S220). The time range setting unit 51 sets the time range X as a search time range when receiving information indicating that the base stations B2 and B3 are receiving GPS signals normally (S230), for example. If the information indicating that the synchronization is not performed is received, the elapsed time indicated by the synchronization state signal is determined (S240).

  Here, for example, in the example shown in FIG. 7 described above, the time range setting unit 51 reads the search time range L corresponding to the elapsed time magnitude T indicated by the synchronization state signal from the data table shown in FIG. As shown in FIG. 7, L1 (S242), L2 (S244), or L3 (S246) is set as a search time range for each of base stations B2 and B3.

  The synchronization signal search unit 44 searches for a synchronization signal included in each signal broadcast from the base stations B2 and B3 within the search time range set by the time range setting unit 51 (S250), and further detects the synchronization signal. If no sync signal is detected from either of the base stations B2 and B3, the search for the sync signal is performed again (S250), and one or more sync signals such as the base stations B2 and B3 are detected. If both of the synchronization signals can be detected, the reception level is determined for each synchronization signal (S270). Then, if it is determined that the reception level is lower than the predetermined value for both the synchronization signals of the base stations B2 and B3, the search for the synchronization signal is performed again (S260), and one or more synchronization signals, for example, the synchronization signal of the base station B2 If it is determined that only the reception level is equal to or higher than the predetermined value, the handover addition process as described above is performed (S280).

  Thus, in this communication system, the base station B broadcasts a synchronization state signal including information indicating the synchronization state between the base station time information and the GPS signal or the reception state of the GPS signal, and the mobile station M A search for a synchronization signal is performed within a time range set based on the synchronization state signal. That is, according to the present invention, the mobile station M can synchronize the time information in the base station and the GPS signal in the other peripheral base stations B2 and B3 different from the currently communicating base station B1 or the GPS signal. Since the synchronization signal can be searched in the time range according to the reception state, synchronization between the mobile station device 40 and the base station device 20 in the cell search or handover is more quickly established than in the conventional communication system, Communication processing can be speeded up and the amount of processing can be reduced, and power consumption can be reduced.

  The present invention is not limited to the above. For example, the synchronization state signal is notified to the base station device 20 (the other base station device 20 adjacent to the base station device 20 with which the mobile station device 40 is communicating) existing in the vicinity of the mobile station device 40 performing the handover process. For example, it may be set according to the communication system status such as the geographical installation status of the base station device 20, the geographical status and movement status of the mobile station device 40, or the quality of the communication line. The synchronization signal broadcast from the base station device 20 is not limited to the pilot signal, and may be any signal that can be used to establish synchronization between the base station device 20 and the mobile station device 40.

  In addition, the GPS signal synchronization state detection unit 30 of the base station device 20 is configured to receive a base signal in the base station device 20 based on at least one of the presence / absence of the reception of the GPS signal and the elapsed time since the last reception of the GPS signal. You may make it generate | occur | produce the reliability information which shows the reliability with respect to the synchronous state of station time information and a GPS signal, and alert | report the synchronous state signal containing this reliability information. In this case, the mobile station M sets a search time range based on the reliability information and searches for a synchronization signal.

  The GPS signal synchronization state detection unit 30 only needs to detect information that affects the transmission timing in the base station device 20, for example, detects the reception level of the GPS signal received by the GPS signal processing unit 26. In the GPS signal processing unit 26, if the GPS signal is normally received but is in an asynchronous state due to some trouble, a synchronization state signal including information on the trouble may be detected.

  The detection of the synchronization state signal in the GPS signal synchronization state detection unit 30 may be performed at a predetermined timing. For example, the synchronization state signal may be matched with the GPS signal notification period or the reception period. It may be performed at a set timing.

  In addition, the time range setting unit 51 of the mobile station device 40 refers to the synchronization state signal received from the base station device 20, refers to the data table as shown in FIG. May be set stepwise or continuously. The search time range in the time range setting unit 51 may be set at a predetermined timing, for example, every time at least one of a synchronization signal and other signals is received from the base station device 20, or the mobile station It may be performed at a timing set in the device 40.

  In addition, in the case where position information is obtained by measuring the propagation delay time between the base station apparatus 20 and the mobile station apparatus 40, the base station in an asynchronous state is taken into account information broadcast from the base station apparatus 40 If the information from the station device 20 is not used, it is possible to prevent deterioration in accuracy of the position information.

It is explanatory drawing which shows the outline | summary of the communication system which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the base station apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the mobile station apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the search time range set in the mobile station apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the main processes in the mobile station apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the base station apparatus which concerns on other embodiment of this invention. It is explanatory drawing which shows the search time range set in the mobile station apparatus which concerns on other embodiment of this invention. It is a figure which shows the data table used for the setting of a search time range in the mobile station apparatus which concerns on other embodiment of this invention. It is a flowchart which shows the main processes in the mobile station apparatus which concerns on other embodiment of this invention.

Explanation of symbols

20 base station apparatus, 21 antenna, 22 antenna, 23 RF processing unit, 24 transmission / reception processing unit, 25 line interface unit, 26 GPS signal processing unit, 30 GPS signal synchronization state detection unit, 31 GPS signal reception detection unit, 32 elapsed time Detection unit, 40 mobile station apparatus, 41 antenna, 42 RF processing unit, 43 transmission / reception processing unit, 44 synchronization signal search unit, 50 control unit, 51 time range setting unit.

Claims (5)

A communication system having a base station apparatus and a mobile station apparatus that transmit and receive signals to and from each other,
The base station apparatus controls a transmission timing of a signal to the mobile station apparatus based on base station time information;
Means for detecting at least one of a synchronization state between the time information in the base station and the GPS signal or a reception state of the GPS signal as a synchronization state signal;
Means for notifying the synchronization state signal to at least one of the mobile station apparatus or another base station apparatus;
The mobile station apparatus, based on the synchronization state signal received from the base station apparatus, a time range setting means for setting a time range for searching for a predetermined synchronization signal broadcast by the base station apparatus;
And a means for searching for the synchronization signal from a signal received from the base station apparatus within a time range set by the time range setting means. A mobile station device that transmits and receives signals to and from a base station device,
A predetermined synchronization signal notified by the base station apparatus based on a synchronization state signal including information indicating at least one of a synchronization state between the base station time information received from the base station apparatus and the GPS signal or a reception state of the GPS signal Time range setting means for setting a time range for searching for,
A mobile station apparatus comprising: means for searching for the synchronization signal from a signal received from the base station apparatus within a time range set by the time range setting means. A base station device that transmits and receives signals to and from a mobile station device,
Means for controlling the transmission timing of the signal to the mobile station device based on the time information in the base station;
Means for detecting at least one of a synchronization state between the time information in the base station and the GPS signal or a reception state of the GPS signal as a synchronization state signal;
A base station apparatus comprising: means for reporting the synchronization state signal to at least one of the mobile station apparatus or another base station apparatus.   The base station apparatus according to claim 3, wherein the synchronization state signal includes information indicating presence / absence of reception of a GPS signal in the base station apparatus. The base station apparatus according to claim 3 or 4, wherein the synchronization state signal includes information indicating an elapsed time since the last GPS signal was received in the base station apparatus.

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