JP2012095148A - Radio base station and assistant method for radio base station system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assistant method for a radio base station system and a radio base station capable of exchanging assistant data with the other stations while reducing the traffic to the minimum necessary level.SOLUTION: A GPS module 150 receives a navigation message from a GPS satellite and generates a reference time signal based on an Ephemeris in prescribed number received by the local station. An unacquired satellite identification part 26 identifies a GPS satellite that does not receive an Ephemeris as an unacquired satellite among the GPS satellites possible to receive the Ephemeris. An inquiry-enabled base station identification part 28 identifies the other radio base station that can receive an Ephemeris from an unacquired satellite based on the Almanac and the positional information of the other radio base stations. The GPS module 150 employs an Ephemeris transmitted from an identified radio base station as an assistant data to receive an Ephemeris from an unacquired satellite.

Description

  The present invention relates to a radio base station and an assist method in a radio base station system, and in particular, a radio base station that receives orbit information from a GPS satellite, and an orbit from the GPS satellite of each radio base station in the radio base station system. The present invention relates to a method for assisting reception of information.

  The radio base station includes a GPS module as a timing acquisition unit in order to align transmission and reception timings. The GPS module acquires information from a plurality of GPS satellites in the sky via a GPS antenna, calculates the correct position and time of the GPS module from the information, and outputs a timing signal thereby. In order to create a correct timing signal, information from four or more GPS satellites is necessary, and accurate information is also required. Therefore, the GPS antenna is generally installed in a place where the sky in the sky is good.

  However, as shown in FIG. 4, the sky view is not always good at all locations. In the example of FIG. 4, the radio base station 601 cannot acquire information from the GPS satellite # 4.

  Moreover, in the indoor radio base station, since the GPS antenna is installed indoors, it is impossible to see the whole sky, and it can be seen only within a certain angle. For this reason, a GPS module corresponding to a method called an assist method, in which GPS satellite orbit information is notified to the GPS module in advance and information from the GPS satellite is acquired using the information, may be used.

  In order to provide satellite orbit information to a GPS module compatible with the assist method, it is necessary to install what is called an assist server.

  In the assist server, the GPS module receives the satellite orbit information and provides the received satellite orbit information to the radio base station. In order to obtain sufficient satellite orbit information, the GPS antenna is installed in a place with a good view of the sky outside. The assist server and the wireless base station are connected via a network such as the Internet. The radio base station acquires the satellite orbit information from the assist server to improve the GPS satellite signal reception sensitivity, calculates the correct position and time of the GPS module from the received information, and outputs a timing signal.

  However, as long as the assist server acquires GPS satellite information using the GPS module, information on all satellites cannot be obtained. For example, as shown in FIG. 5, GPS satellite # 1 and GPS satellite # 2 can be received because they are above the horizon when viewed from the assist server 701, but GPS satellite # 3 is below the horizon, Cannot receive. At this time, even if there is a radio base station that requires information from the GPS satellite # 3, the information cannot be provided from the assist server, and therefore this radio base station cannot output a correct timing signal. In addition, when a failure occurs in the assist server, the GPS module of the radio base station cannot obtain assist information, and thus cannot output a correct timing signal as described above.

  As means for solving such a state, a method of exchanging assist data between GPS modules connected to a network as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2005-49296) is shown. In this method, communication between GPS modules is performed in a wireless network area such as BLUE TOOTH.

JP 2005-49296 A

  However, when the method described in Patent Document 1 is applied to a radio base station that is fixedly arranged at a position spaced apart by a certain distance or more, the radio base station is connected to the backhaul, and the transmission request for assist data is performed. , And reply transmission of assist data in response to the transmission request are communicated through the backhaul. Therefore, an assist data transmission request is sent to all radio base stations, and an assist data reply transmission is also sent to all radio base stations. As a result, there is a problem that the amount of traffic prepared in the terminal connected to the radio base station in the backhaul is compressed. Further, even in a radio base station that does not hold assist data, it is necessary to check whether or not the own station holds assist data, and wasteful processing occurs.

  Therefore, an object of the present invention is to provide a radio base station capable of exchanging assist data with other stations while minimizing traffic, and an assist method in the radio base station system.

  In order to solve the above problems, a radio base station according to the present invention receives a navigation message including an almanac and an ephemeris from a GPS satellite, and generates a reference time signal based on a predetermined number of ephemeris received by the local station. Among the GPS satellites that can be received at the current time, the GPS unit that has not received the ephemeris as an unacquired satellite, the unacquired satellite identification unit, the almanac, and the position information of other radio base stations Based on this, a base station identifying unit that identifies another radio base station that can receive an ephemeris from an unacquired satellite and a request to transmit the ephemeris of the unacquired satellite to the identified other radio base station An ephemeris request unit, and the GPS reception unit uses the ephemeris transmitted from the specified radio base station as assist data. Te, to receive the ephemeris from the non-acquired satellite.

  According to the radio base station of the present invention, it is to provide a radio base station capable of exchanging assist data with other stations while minimizing traffic.

It is a figure showing the structure of the radio base station system of embodiment of this invention. It is a figure showing the structure of the wireless base station of embodiment of this invention. It is a flowchart which shows the operation | movement procedure of the radio base station of embodiment of this invention. It is a figure for demonstrating the example of the conventional system. It is a figure for demonstrating the example of the conventional system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(overall structure)
FIG. 1 is a diagram showing a configuration of a radio base station system according to an embodiment of the present invention.

  Referring to FIG. 1, this radio base station system is a base station system composed of a plurality of radio base stations that acquire frame synchronization by GPS.

  This radio base station system includes a plurality of radio base stations 15a to 15h. A plurality of wireless base stations 15a to 15h are connected by a wired network 52. The plurality of radio base stations 15a to 15h include GPS modules 150a to 150h, respectively. The GPS modules 150a to 150h receive navigation messages (orbit information) from a plurality of GPS satellites belonging to the GPS satellite group (32 GPS satellites) by the GPS antennas 52a to 52h.

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

  The radio base station 15 includes a GPS antenna 12, a GPS module 150, a radio antenna 14, a radio communication unit 16, a data acquisition unit 18, a satellite data storage unit 20, a coordinate information storage unit 24, and an unacquired A satellite specifying unit 26, an address storage unit 30, an inquiryable base station specifying unit 28, an ephemeris requesting unit 34, an ephemeris providing unit 32, and a network interface 36 are provided.

  The GPS module 150 includes a GPS antenna 12 and receives a navigation message through the GPS antenna 12. The navigation message includes the orbit information (ephemeris) of the GPS satellite that transmitted the navigation message and the orbit information (almanac) of all GPS satellites. The almanac is superimposed on navigation messages from all satellites, and includes rough position information for all GPS satellites. The ephemeris contains accurate position information of the GPS satellite that transmitted it.

  The GPS module 150 identifies the GPS satellite in the visible position based on the almanac, the position of the device itself, and the approximate time. The GPS module 150 receives an ephemeris among navigation messages from GPS satellites in a visible position. When the GPS module 150 cannot receive a GPS satellite at a visible position, the GPS module 150 uses the ephemeris of the GPS satellite received by another radio base station to increase the reception sensitivity of the ephemeris of the GPS satellite. Receives ephemeris from GPS satellites.

  The GPS module 150 generates an accurate reference time signal tb by using the ephemeris of the four satellites received by the own station, the position of the own device, and the approximate time held.

  The data acquisition unit 18 extracts individual orbit information, that is, almanac and ephemeris, from the navigation message received by the GPS module 150 and stores them in the satellite data storage unit 20. The data acquisition unit 18 deletes the data because the validity of the data is lost when a predetermined time elapses after the almanac or ephemeris is stored in the satellite data storage unit 20.

  The coordinate information storage unit 24 stores the position information of all the radio base stations of the radio base station system corresponding to this system.

  The address storage unit 30 stores the IP address of the radio base station of the radio base station system corresponding to this system.

  The unacquired satellite specifying unit 26 determines whether the current ephemeris is present at the local station based on the current time, the position information of the local station stored in the coordinate information storage unit 24, and the almanac. One or more receivable GPS satellites are identified as visible satellites. The unacquired satellite specifying unit 26 specifies one or more GPS satellites that have not received the ephemeris among the one or more visible satellites at the current time as unacquired satellites.

  Based on the almanac and the position information of other radio base stations stored in the coordinate information storage unit 24, the inquireable base station specifying unit 28 is a time earlier than the current time by a predetermined time (for example, about 1 hour). Then, one or more other radio base stations that were able to receive the ephemeris from the unacquired satellite are identified as inquireable base stations. Here, the reason why the time is a predetermined time (for example, about one hour) earlier than the current time is to obtain information already acquired by other radio base stations. The inquiryable base station can be identified by performing the same calculation only by specifying the visible satellite of the GPS module 150 and the unacquired satellite specifying unit 26, and changing the base station coordinates from the own station to the position of another radio base station. Can be done.

  The principle of the calculation method necessary for identifying the visible satellite and the inquiry base station is, for example, “No GPS satellite orbit calculation, Electronic Navigation Research Institute, Shonosuke Fukushima, Aviation Radio, No. 34-36. And the like.

  The ephemeris request unit 34 reads out the IP address of the inquireable base station from the address storage unit 30, and requests to transmit the ephemeris of the unacquired satellite through the network interface 36 with the read IP address as the destination address. The ephemeris request unit 34 outputs the ephemeris to the GPS module 150 when the ephemeris can be received from the inquireable base station. When the ephemeris request unit 34 cannot receive the ephemeris from the inquireable base station, the ephemeris request unit 34 requests another radio base station to transmit the ephemeris again. The ephemeris request unit 34 repeats this process to acquire a required ephemeris from another radio base station and outputs it to the GPS module 150.

  When the ephemeris providing unit 32 receives an ephemeris transmission request for an unacquired satellite from another wireless base station through the network interface 36, the ephemeris for the unacquired satellite stored in the satellite data storage unit 20 is stored. The ephemeris is transmitted to the requested radio base station through the network interface 36, and a message indicating that there is no such ephemeris is transmitted through the network interface 36.

  The network interface 36 receives ephemeris data from another radio base station or receives an ephemeris data transmission request via the network 52, and transmits the femeris data to the other radio base station.

  The wireless communication unit 16 performs communication processing of a signal received from the wireless antenna 14 and a signal output from the wireless antenna 14 in synchronization with the reference time signal tb output from the GPS module 150.

(Operation)
FIG. 3 is a flowchart showing an operation procedure of the radio base station according to the embodiment of the present invention.

Referring to FIG. 3, first, GPS module 150 is activated (step S101).
The GPS module 150 receives a navigation message through a GPS antenna. The GPS module 150 identifies the GPS satellite in the visible position based on the almanac, the position of the device itself, and the approximate time. The GPS module 150 receives an ephemeris among navigation messages from GPS satellites in a visible position. If the GPS module 150 cannot receive the ephemeris of the GPS satellite in the visible position, the ephemeris of the GPS satellite is received using the ephemeris of the GPS satellite received by the other radio base station acquired in step S111 described later. By increasing the reception sensitivity, the ephemeris of the GPS satellite is received (step S102).

  Next, when four or more ephemeris are acquired by the GPS module 150 and stored in the satellite data storage unit 20 (YES in step S103), the GPS module 150 receives four GPS satellites received by the local station. An accurate reference time signal tb is generated using the ephemeris, the position of the own device, and the approximate time of possession (step S104).

  If four or more ephemeris are acquired and not stored in the satellite data storage unit 20 (NO in step S103), the unacquired satellite specifying unit 26 stores the current time in the coordinate information storage unit 24. Based on the position information of the local station and the almanac, the GPS satellite that should be currently visible at the local station, that is, the GPS satellite that can be received by the ephemeris at the local station is identified as a visible satellite k (k = 1 to K). Here, it is assumed that K visible satellites have been identified (step S105).

  The unacquired satellite specifying unit 26 receives the number of the GPS satellite currently receiving the ephemeris from the data acquiring unit 18, and among the visible satellites k (k = 1 to K), the GPS satellites that are not currently receiving the ephemeris Is identified as an unacquired satellite i (i = 1 to N). Here, it is assumed that N unacquired satellites have been identified (step S106).

The inquireable base station identification unit 28 sets the control variable i to 1 (step S107).
Next, based on the almanac and the position information of the other radio base stations stored in the coordinate information storage unit 24, the inquireable base station specifying unit 28 is only a predetermined time (for example, about 1 hour) from the current time. Another radio base station that can receive the ephemeris from the unacquired satellite i at an early time is identified as a queryable base station j (j = 1 to M).

The ephemeris request unit 34 sets the control variable j to 1 (step S109).
The ephemeris request unit 34 reads the IP address of the inquireable base station j from the address storage unit 30, and requests to transmit the ephemeris of the unacquired satellite i through the network interface 36 with the read IP address as the destination address. (Step S110).

  If the ephemeris of the unacquired satellite i is stored in the satellite data storage unit 20, the ephemeris providing unit 32 of the inquireable base station j returns the ephemeris of the unacquired satellite i and returns to the satellite data storage unit 20. When the ephemeris of the acquisition satellite i is not stored, a reply that the ephemeris of the unacquired satellite i is not acquired is returned.

  When the ephemeris request unit 34 receives the ephemeris from the inquireable base station j (YES in step S111), the ephemeris request unit 34 outputs the ephemeris to the GPS module 150 and returns to step S103.

  When the ephemeris request unit 34 cannot receive the ephemeris from the inquireable base station j (NO in step S111) and j is not M (NO in step S112), j is incremented by 1 (step S113). Return to step S110.

  On the other hand, if the ephemeris request unit 34 cannot receive the ephemeris from the inquireable base station j (NO in step S111), j = M (YES in step S112), and i = N is not satisfied (step S114). NO), i is incremented by 1 (step S115), and the process returns to step S108.

  On the other hand, when the ephemeris request unit 34 cannot receive the ephemeris from the inquireable base station j (NO in step S111), j = M (YES in step S112), and i = N (step S114). YES), waits for a certain time (step S116), and returns to step S102.

(effect)
As described above, according to the embodiment of the present invention, even if the radio base station system does not have an assist server, the radio base station can use the GPS module using the assist function, and can acquire orbit information. Because of this, traffic can be minimized.

(Modification)
The present invention is not limited to the above embodiment, and includes, for example, the following modifications.

  In the embodiment of the present invention, the ephemeris request unit sequentially selects one from among a plurality of queryable base stations, requests the selected queryable base station to transmit the ephemeris, and sends the ephemeris from the base station. If it can be received, then the ephemeris transmission is not requested to the other inquiryable base station. However, the present invention is not limited to this.

  The ephemeris request unit requests transmission of ephemeris to a plurality of inquireable base stations, selects the ephemeris having the most probable value representing the orbit from the ephemeris received from these base stations, and outputs the selected ephemeris to the GPS module. It is good as well.

  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.

  12 GPS antennas, 14 wireless antennas, 16 wireless communication units, 18 data acquisition units, 20 satellite data storage units, 24 coordinate information storage units, 26 unacquired satellite identification units, 28 inquiryable base station identification units, 30 address storage units, 32 ephemeris providing unit, 34 ephemeris requesting unit, 36 network interface, 52 network, 15, 15a to 15h radio base station, 150, 150a to 150h GPS module.

Claims (6)

A GPS receiver that receives a navigation message including an almanac and an ephemeris from a GPS satellite, and generates a reference time signal based on a predetermined number of ephemeris received by the own station;
An unacquired satellite identifying unit that identifies a GPS satellite that has not received the ephemeris as an unacquired satellite among GPS satellites that can be received by the ephemeris at a current time;
A base station specifying unit for specifying an almanac and another radio base station capable of receiving an ephemeris from the unacquired satellite based on position information of the other radio base station;
An ephemeris request unit that requests the identified other radio base station to transmit the ephemeris of the unacquired satellite;
The GPS reception unit is a radio base station that receives an ephemeris from the unacquired satellite by using an ephemeris transmitted from the identified radio base station as assist data.   The base station identification unit is configured to receive another ephemeris from the unacquired satellite at a time earlier than the current time by a predetermined time based on the position information of the almanac and other radio base stations. The radio base station according to claim 1, wherein the station is specified. The radio base station further includes:
An address storage unit for storing IP addresses of a plurality of radio base stations;
The ephemeris request unit reads out the IP address of the specified radio base station from the address storage unit, and requests to transmit the ephemeris of the unacquired satellite with the read IP address as a destination address. The radio base station according to claim 1.   The radio base station according to claim 1, wherein the unacquired satellite identifying unit identifies a GPS satellite that can be received by the current ephemeris by the local station based on the current time, the position of the local station, and the almanac. The radio base station further includes:
If the ephemeris of the unacquired satellite is stored when the ephemeris transmission request of the unacquired satellite is received from another radio base station, the stored ephemeris is sent to the other radio base station. The radio base station according to claim 1, further comprising an ephemeris providing unit for transmission. An assist method in a radio base station system in which a plurality of radio base stations are connected through a network,
The first radio base station specifies GPS satellites that have not received the ephemeris as unacquired satellites among GPS satellites that can be received by the ephemeris at the current time;
The first radio base station identifies a second radio base station capable of receiving an ephemeris from the unacquired satellite based on almanac and position information of another radio base station;
The first radio base station requesting the identified second radio base station to transmit an ephemeris of the unacquired satellite;
If the second radio base station stores the ephemeris of the unacquired satellite when the ephemeris transmission request of the unacquired satellite is received, the stored ephemeris is stored in the first ephemeris. Transmitting to the radio base station;
The first radio base station receives an ephemeris from the unacquired satellite using the ephemeris transmitted from the second radio base station as assist data;
An assist method in a radio base station system, comprising: generating a reference time signal based on a predetermined number of ephemeris received by the first radio base station.

Images