JP2011109165A - Radio communication system, method of calculating error time, and method of acquiring time synchronization between base stations - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system comprising a base station and an auxiliary base station, and capable of acquiring time synchronization between the base stations even when only the base station is mounted with a GPS receiver, a method of calculating error time in the system, and a method of acquiring time synchronization between the base stations. <P>SOLUTION: This radio communication system includes a base station 1 for receiving a GPS signal 5, and an auxiliary base station 2 connected with the base station 1 via a dedicated line 3, without receiving the GPS signal 5. The base station 1 transmits/receives a temporal error signal to/from the auxiliary base station 2, and measures an error time of the auxiliary base station 2 with respect to the base station 1 based on a transmission time of the temporal error signal in the base station 1, a reception time in the auxiliary base station 2, a transmission estimated time to the base station 1 from the auxiliary base station 2, and a reception time in the base station 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention comprises a base station equipped with a GPS (Global Positioning System) receiver and an auxiliary base station not equipped with a GPS receiver. The present invention relates to acquisition of time synchronization between base stations in a wireless communication system capable of transmission.

  In a wireless communication system that realizes simultaneous multi-station transmission, it is necessary to establish time synchronization between base stations. Conventionally, time information from a GPS receiver has not been used for time synchronization between base stations, and time synchronization between base stations has been realized by supplying a synchronization signal from the outside.

  However, in such a system, the time synchronization of each base station cannot be achieved when the synchronization signal is not supplied from the outside of the base station.

  In Patent Document 1, GPS receivers are mounted on all base stations and auxiliary base stations, and it is assumed that each base station is synchronized in time using time information of GPS signals. A method for calculating the transmission timing from each base station is disclosed.

Japanese Patent No. 3376444

  As in Patent Document 1, when GPS receivers are installed in all base stations and auxiliary base stations, time synchronization between base stations can be achieved using time information of GPS signals. When a GPS receiver is mounted only on a base station, time synchronization between the base stations cannot be achieved, and simultaneous transmission of multiple stations cannot be performed.

  Therefore, in view of the above-described problems, the present invention is a wireless communication system including a base station and an auxiliary base station, and even when only the base station is equipped with a GPS receiver, time synchronization between base stations is achieved. It is an object of the present invention to provide a wireless communication system capable of performing the above, a method for calculating an error time in the system, and a method for acquiring time synchronization between base stations.

  The wireless communication system of the present invention includes a base station that receives a GPS signal, and an auxiliary base station that is connected to the base station through a dedicated line and does not receive a GPS signal. The base station is connected to the auxiliary base station and a time error signal. The base station of the auxiliary base station based on the transmission time of the time error signal at the base station, the reception time at the auxiliary base station, the scheduled transmission time from the auxiliary base station to the base station, and the reception time at the base station Measure the error time for the station.

  The error time calculation method in the wireless communication system of the present invention includes (a) a step of storing a transmission time of a time error signal transmitted from a base station to an auxiliary base station in the base station, and (b) an auxiliary base station. A time error signal reception time and a scheduled transmission time of the time error signal from the auxiliary base station to the base station in the time error signal, and (c) a step of storing the reception time in the base station in the base station And (d) measuring at the base station the error time of the auxiliary base station with respect to the base station based on the transmission time and reception time of the base station, and the reception time and scheduled transmission time of the auxiliary base station.

  In the inter-base station time synchronization acquisition method of the present invention, the time of the auxiliary base station is synchronized with the time of the base station using the error time of the auxiliary base station with respect to the base station measured by the error time calculation method.

  The wireless communication system of the present invention includes a base station that receives a GPS signal, and an auxiliary base station that is connected to the base station through a dedicated line and does not receive a GPS signal. The base station is connected to the auxiliary base station and a time error signal. The base station of the auxiliary base station based on the transmission time of the time error signal at the base station, the reception time at the auxiliary base station, the scheduled transmission time from the auxiliary base station to the base station, and the reception time at the base station Measure the error time for the station. Thereby, even if the auxiliary base station cannot receive the GPS signal, the error time for the base station can be known by transmitting and receiving the time error signal with the base station.

  The method for calculating an error time in the wireless communication system of the present invention includes a step of storing a transmission time of a time error signal transmitted from a base station to an auxiliary base station in the base station, and reception of the time error signal in the auxiliary base station. A step of describing the time and a scheduled transmission time of the time error signal from the auxiliary base station to the base station in the time error signal, a step of storing the reception time in the base station in the base station, and a transmission time and reception of the base station Measuring the error time of the auxiliary base station with respect to the base station based on the time, the reception time of the auxiliary base station, and the scheduled transmission time. Thereby, even if the auxiliary base station cannot receive the GPS signal, the base station can measure the error time of the auxiliary base station through transmission / reception of the time error time with the base station.

  In the inter-base station time synchronization acquisition method of the present invention, the time of the auxiliary base station is synchronized with the time of the base station using the error time of the auxiliary base station with respect to the base station measured by the error time calculation method. Thereby, even if an auxiliary base station cannot receive a GPS signal, time synchronization between base stations can be achieved.

1 is an overall configuration diagram of a radio communication system according to the present invention. 3 is a flowchart showing operations of a base station and an auxiliary base station in the inter-base station time synchronization method of the present invention. It is a figure explaining the method of calculating the correction time of an auxiliary base station.

(Embodiment 1)
<Configuration>
FIG. 1 is a schematic diagram showing an entire wireless communication system that realizes multi-station simultaneous communication according to the first embodiment. The wireless communication system according to the first embodiment includes a base station 1, an auxiliary base station 2 connected to the base station 1 through a dedicated line 3, a GPS satellite 4 that transmits a GPS signal 5 to the GPS antenna 6 of the base station 1, . In the communication area 9 of the base station 1, the portable radio 11 can receive a radio signal 13 from the base station 1, and in the communication area 10 of the auxiliary base station 2, the portable radio 12 is wireless from the auxiliary base station 2. The signal 14 can be received. A signal from the base station 1 to the auxiliary base station 2 is a downlink signal 7, and a signal from the auxiliary base station 2 to the base station 1 is an uplink signal 8. The auxiliary base station 2 cannot receive GPS signals.

  Although one auxiliary base station is shown in FIG. 1, a plurality of auxiliary base stations may be provided for the base station 1.

<Time synchronization method between base stations>
The inter-base station time synchronization method between the base station 1 and the auxiliary base station 2 using the GPS signal will be described with reference to FIG. FIG. 2 is a flowchart showing the operations of the base station 1 and the auxiliary base station 2 in the process of time synchronization performed before starting the simultaneous multi-station communication.

  When the base station 1 receives the GPS signal 5 (step S1), the base station 1 corrects the time in the base station 1 based on the GPS time information of the GPS signal 5 (step S2). The base station 1 generates a time error signal (step S3), and transmits the time error signal to the auxiliary base station 2 via the dedicated line 3 (step S4). The transmission time is stored in the base station 1 (step S5).

  The auxiliary base station 2 that has received the time error signal from the base station 1 via the dedicated line 3 adds the time error signal reception time and the time error signal scheduled transmission time to the base station 1 to the time error signal (step S6). ). At this time, the reception time of the time error signal includes the time error inside the auxiliary base station 2 and the propagation delay error due to the dedicated line 3, and the time error signal transmission scheduled time includes the time error inside the auxiliary base station 2. include. The auxiliary base station 2 returns the additionally written time error signal to the base station 1 via the dedicated line 3 (step S7).

  The base station 1 that has received the time error signal from the auxiliary base station 2 stores the reception time (step S8). The base station 1 determines the time correction value in the auxiliary base station 2 based on the transmission time and reception time of the time error signal in the base station 1 and the reception time and scheduled transmission time in the auxiliary base station 2 added to the time error signal. That is, the error time of the auxiliary base station 2 with respect to the base station 1 is calculated (step S9). A method for calculating the time correction value will be described in detail later. The base station 1 generates a time correction value signal from the calculated time correction value in the auxiliary base station 2 (step S10) and transmits it to the auxiliary base station 2 via the dedicated line 3 (step S11).

  The auxiliary base station 2 receives the time correction value signal from the base station 1 and corrects its own time (step S12). When the time correction is completed, the auxiliary base station 2 transmits a time correction completion notification to the base station 1 via the dedicated line 3 (step S13).

  As described above, the wireless communication system according to the present embodiment includes the base station 1 that receives the GPS signal 5 and the auxiliary base station 2 that is connected to the base station 1 through the dedicated line 3 and does not receive the GPS signal 5. Is a wireless communication system. The base station 1 transmits / receives a time error signal to / from the auxiliary base station 2, and the transmission time of the time error signal at the base station 1, the reception time at the auxiliary base station 2, and the scheduled transmission time from the auxiliary base station 2 to the base station 1 And the error time of the auxiliary base station 2 with respect to the base station 1 is measured based on the reception time at the base station 1. Then, the time of the auxiliary base station 2 is synchronized with the time of the base station 1 using the error time of the auxiliary base station 2 with respect to the base station 1. Thereby, even if it is the environment where only the base station 1 can receive the GPS signal 5, it can synchronize between base stations.

  Further, the error time calculation method of the present embodiment is an error time calculation method in the radio communication system, and the base station 1 stores the transmission time of the time error signal transmitted from the base station 1 to the auxiliary base station 2. A step of describing the time error signal reception time at the auxiliary base station 2 and a scheduled transmission time of the error signal from the auxiliary base station 2 to the base station 1 in the time error signal; The base station 1 sets the error time of the auxiliary base station 2 relative to the base station 1 based on the steps stored in the station 1, the transmission time and reception time of the base station 1, and the reception time and scheduled transmission time of the auxiliary base station 2. Measuring. Thereby, even in an environment where only the base station 1 can receive a GPS signal, the time error of the auxiliary base station 2 with respect to the base station 1 can be known.

  Further, the inter-base station time synchronization acquisition method of the present embodiment uses the error time of the auxiliary base station 2 with respect to the base station 1 measured by the above error time calculation method to set the time of the auxiliary base station 2 to the base station 1. Synchronize with the time. Thereby, even if it is the environment where only the base station 1 can receive a GPS signal, synchronization between base stations can be taken.

<Time correction value calculation method>
A method for calculating the time correction value of the auxiliary base station 2 will be described with reference to FIG. Assume that DL_Delay is the downlink delay time in the downlink signal 7 from the base station 1 to the auxiliary base station 2, UL_Delay is the uplink delay time in the uplink signal 8 from the auxiliary base station 2 to the base station 1, and DL_Delay = UL_Delay. The value that the base station 1 wants to calculate is the time correction value of the auxiliary base station 2 = error (Err_semi). The values that are known when the time error signal is received from the auxiliary base station 2 at the base station 1 are the transmission time TX_base at the base station 1, the reception time RX_base at the base station 1, and the reception time RX_semi_meas at the auxiliary base station 2. There are four scheduled transmission times TX_semi_meas at the auxiliary base station 2.

  There is an error between the reception time RX_base and the scheduled transmission time TX_semi_meas at the auxiliary base station 2, and when the time synchronized with the time of the base station 1 is RX_semi, the reception time RX_base and the scheduled transmission time TX_semi_meas are expressed as follows: Is done.

  The downlink delay time DL_Delay_meas including the error in the dedicated line 3 calculated by the base station 1 based on the information from the auxiliary base station 2 is expressed as follows.

  Further, the uplink delay time UL_Delay_meas including the error in the dedicated line 3 calculated by the base station 1 based on the information from the auxiliary base station 2 is expressed as follows.

  From the assumption that DL_Delay = UL_Delay, the following equation is obtained.

  Therefore, the error Err_semi at the auxiliary base station 2 can be estimated as follows.

<Effect>
The wireless communication system of the present embodiment has the following effects as already described. That is, the wireless communication system of the present embodiment includes a base station 1 that receives a GPS signal 5 and an auxiliary base station 2 that is connected to the base station 1 through a dedicated line 3 and does not receive the GPS signal 5. In this wireless communication system, the base station 1 transmits and receives a time error signal to and from the auxiliary base station 2, transmits the time error signal at the base station 1, receives the time at the auxiliary base station 2, 1, the error time of the auxiliary base station 2 with respect to the base station 1 is measured based on the scheduled transmission time to 1 and the reception time at the base station 1. Thereby, even in an environment where only the base station 1 can receive a GPS signal, the time error of the auxiliary base station 2 with respect to the base station 1 can be known.

  Then, the time of the auxiliary base station 2 is synchronized with the time of the base station 1 using the error time of the auxiliary base station 2 with respect to the base station 1. Thereby, even if it is the environment where only the base station 1 can receive the GPS signal 5, it can synchronize between base stations.

  Further, the error time calculation method of the present embodiment is an error time calculation method in the radio communication system, and the base station 1 stores the transmission time of the time error signal transmitted from the base station 1 to the auxiliary base station 2. A step of describing the time error signal reception time at the auxiliary base station 2 and a scheduled transmission time of the error signal from the auxiliary base station 2 to the base station 1 in the time error signal; The base station 1 sets the error time of the auxiliary base station 2 relative to the base station 1 based on the steps stored in the station 1, the transmission time and reception time of the base station 1, and the reception time and scheduled transmission time of the auxiliary base station 2. Measuring. Thereby, even in an environment where only the base station 1 can receive a GPS signal, the time error of the auxiliary base station 2 with respect to the base station 1 can be known.

  Further, the inter-base station time synchronization acquisition method of the present embodiment uses the error time of the auxiliary base station 2 with respect to the base station 1 measured by the above error time calculation method to set the time of the auxiliary base station 2 to the base station 1. Synchronize with the time. Thereby, even if it is the environment where only the base station 1 can receive a GPS signal, synchronization between base stations can be taken.

  INDUSTRIAL APPLICABILITY The present invention can be used when there is no signal supply in order to achieve synchronization between base stations in a wireless communication system that realizes simultaneous multi-station communication.

  1 base station, 2 auxiliary base station, 3 dedicated line, 4 GPS satellite, 5 GPS signal, 6 GPS antenna, 9 base station communication area, 10 auxiliary base station communication area, 11, 12 portable radio.

Claims (4)

A wireless communication system comprising a base station that receives a GPS signal, and an auxiliary base station that is connected to the base station via a dedicated line and does not receive a GPS signal,
The base station transmits and receives a time error signal with the auxiliary base station,
The auxiliary base based on the transmission time of the time error signal at the base station, the reception time at the auxiliary base station, the scheduled transmission time from the auxiliary base station to the base station, and the reception time at the base station A radio communication system, characterized in that an error time of a station with respect to the base station is measured.   The radio communication system according to claim 1, wherein the time of the auxiliary base station is synchronized with the time of the base station using an error time of the auxiliary base station with respect to the base station. An error time calculation method in a wireless communication system comprising a base station that receives a GPS signal and an auxiliary base station that is connected to the base station via a dedicated line and does not receive a GPS signal,
(A) storing a transmission time of a time error signal transmitted from the base station to the auxiliary base station in the base station;
(B) describing the time error signal reception time at the auxiliary base station and the scheduled transmission time of the time error signal from the auxiliary base station to the base station in the time error signal;
(C) storing the reception time at the base station at the base station;
(D) measuring an error time of the auxiliary base station with respect to the base station based on the transmission time and reception time of the base station and the reception time and scheduled transmission time of the auxiliary base station at the base station. An error time calculation method comprising:   The time of the auxiliary base station is synchronized with the time of the base station using the error time of the auxiliary base station with respect to the base station measured by the error time calculation method according to claim 3, Inter-station time synchronization acquisition method.

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