JPH0969811A - Correcting method of synchronizing signal between base stations - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the synchronous correction of systems by using a reference clock supplied from a wired transmission line and a system frame signal in order to attain the synchronization of plural base stations, receiving a frame synchronizing signal transmitted from another base station and calculating the delay of the synchronizing signal from that frame signal corresponding to the reference clock mentioned above. SOLUTION: A reference clock CLK and a system frame signal SYS-FS of 8kHz are inputted from a wired transmission line 14 of a high-speed digital communication network while using a synchronizing corrector composed of an antenna, RF part 13, radio control part 10, differential calculation logic 11 and delay logic 12. On the other hand, a radio frame synchronizing signal FSYNC (A) of another base station under transmission is inputted from the radio control part 10, delay time Td of the radio frame synchronizing signal FSYNC (A) from the system frame signal SYS-FS is calculated by the differential calculation logic 11, the delay of the system frame signal SYS-FS is corrected by the delay logic 12, and a frame synchronizing signal FSYNC is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to inter-base station synchronization in a mobile communication system using a time division multiplex wireless line (particularly PHS and digital cellular) for achieving frame synchronization between base stations by a wired line. The present invention relates to a signal correction method.

[0002]

2. Description of the Related Art When a radio signal is synchronized between a plurality of radio base stations by a time division multiplex radio link between a radio base station and a mobile terminal, conventionally, all transceivers are used to establish the synchronization. The wireless base station is provided with the wireless base station and wireless communication is performed with an adjacent base station for synchronization, or a reference base station is provided and the wireless base station receives a reference signal from the reference base station and There is also proposed a system in which base stations are synchronized with each other by a received signal. There is also a system in which a reference signal is transmitted from a reference station via a wire or the like, and each base station transmits it to a mobile station in synchronization with this reference signal.

By the way, in the case of PHS, the wireless zone is made into a small area, and a PHS base station is connected to a telephone line network of ISDN line or analog line as a repeater and installed on the roof of a building to form a service area, The mobile terminals in the area are communicated by radio waves to communicate with a general telephone connected to a telephone line.

In such a communication system, as shown in FIG. 5, a public telecommunication network or a private network 5 is used.
4 through a local exchange or a private branch exchange 53, connect to the exchange 53 via a subscriber transmission line or a private transmission line 55, and connect from the line control unit 52 to a line transmission line 56 to a base station. Connect to station 50 or base station 51,
The base station 50 and the base station 51 communicate with the mobile station 60, respectively.

However, the wire transmission path 56 connecting the base stations 50/51 to each other differs in propagation delay time due to differences in transmission distance, thickness of transmission path, material, etc.
In the case of N, the system reference clock of 8 kHz is used, but there is a problem that the frame phase is not constant due to a phase difference between the clocks, and due to jitter and the like due to yearly temperature fluctuations and deterioration of repeaters over time. is there.

[0006]

In order to solve this problem, the following measures have been taken conventionally. 1) The length, thickness, and material of the wire are limited, and the supplied frame synchronization signal is used as it is, or the synchronization deviation is corrected by a fixed value. 2) Make fine adjustments manually using a measuring instrument or jig when installing. However, in the above measure 1), since a fixed value is used, accurate synchronization cannot be achieved. Further, in the case of the above-mentioned 2) manual fine adjustment, an excessive amount of labor is required for maintenance related to synchronization when a power failure or failure occurs.

In order to achieve the above object, it is an object of the present invention to provide a method for correcting a synchronization signal between base stations, which enables accurate synchronization between base stations with a simple circuit configuration. To do.

[0008]

Therefore, the present invention uses a reference clock signal supplied from a wired transmission line of a high-speed transmission digital communication network and a system frame signal generated from the reference clock signal, while The base station receives the frame signal transmitted by the base station, calculates the delay of the system frame signal with respect to the frame signal by the reference clock through the difference calculation logic, corrects the system frame signal by the delay logic, and corrects the base frame. We propose a synchronization signal correction method between base stations for synchronization between stations. That is, the present invention is a mobile communication system comprising a plurality of radio base stations, wherein each of the base stations is connected to a plurality of mobile stations via a time division multiplex radio line, and each base station is a wire line for frame timing synchronization. In the system, the difference between the system frame signal generated from the system reference clock supplied from the wired circuit and the wireless frame signal received from another base station is converted into the reference clock count number by the difference calculation logic, and the converted value is obtained. Is used to correct the system frame signal generated from the system reference clock by the delay logic.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be described together with the illustrated example. However, unless otherwise specified, the dimensions, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent. FIG.
2 is a block diagram showing an outline of an inter-base station synchronization signal correction apparatus to which the present invention is applied, FIG. 2 is a timing chart of the correction in FIG. 1, and FIG. 3 is a flowchart showing the operation status of FIG.

As shown in FIG. 1, the present apparatus has an antenna 1
3a, an RF unit 13, a wireless control unit 10, a difference calculation logic 11, and a delay logic 12, and is a system locked from a wired transmission line 14 of a high-speed digital communication network to 8 kHz or 8 kHz as shown in the time chart of FIG. The reference clock CLK and the system frame signal SYS-FS generated from the clock are applied to the delay logic 1
2 while inputting the radio control unit 10 to the “IN” state, the radio frame signal FSYNC (A) of another base station being transmitted is input from the antenna 13a to the difference calculation logic 11 from the radio control unit 10, The logic 11 uses the reference clock CLK to generate the wireless frame signal FSYNC.
The delay time Td for the system frame signal SYS-FS in (A) is calculated, and Td-Ta = Ts (Ta is CLK
(Correction value for adjusting to) is converted into the count number of the reference clock, and the system frame signal SYS-FS is delayed and corrected by the delay logic 12 by the converted value to obtain the frame signal FSYNC.

As for the operation procedure, as shown in the flowchart of FIG. 3, the delay logic 12 is initialized and a predetermined default value is set. (S15) Next, the wireless frame signal FSYNC (A) of the other base station being transmitted from the antenna 13a is received by setting the wireless controller 10 to the "IN" state (S16), and then the frame signal FSYNC (A). If it is received after determining in (S17) whether or not is received (S18)
The system frame signal SYS input from the wired transmission line 14 of the high speed digital communication network by the difference calculation logic 11.
The difference from −FS is read with the count value converted by the reference clock CLK, and after an error determination such as the range of the count value is made in (S19), the count value is set in the delay logic in (S20) to perform synchronization correction. Then (S21)
Then, the radio control unit 10 is set to “OUT” to operate the base station based on the corrected frame synchronization signal FSYNC. In addition, in (S17), the frame signal FSYN of another base station
If C (A) has not been received, or if the correct count value cannot be obtained in (S19), synchronization correction is performed based on a preset default value.

Since the correction difference is calculated based on the system reference clock CLK given from the wired digital network as described above, it goes without saying that the frequency accuracy of the reference clock is guaranteed. is there.

[0013]

As described above, according to the present invention, if the frequency accuracy of the reference clock supplied from the digital network is guaranteed, it depends on the thickness, length, material, etc. of the wire forming the transmission line. It is possible to realize highly accurate synchronization between base stations. Therefore, according to such an invention, as shown in FIG. 4, in addition to the parallel connection of the conventional digital network 54-base stations A and B50, the base stations F and C51, the base station C51 and the grandchild base station D and Since the base station E59 can be synchronized even under free connection, not only can the base station be planned, designed, and installed according to the service purpose, but also the effective use of frequencies can be facilitated. Therefore, a high-quality call can be secured even when the base stations are combined in series or in parallel in a place where radio waves do not reach, such as in a building, in the shadow of a building, or in an underground mall.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a synchronization signal correction apparatus to which a method for correcting a synchronization signal between base stations of the present invention is applied.

FIG. 2 is a timing chart of the device in FIG.

FIG. 3 is a flowchart showing an operation procedure of FIG.

FIG. 4 is a schematic diagram of a mobile communication system applied by the present invention.

FIG. 5 is a schematic diagram showing a conventional mobile communication system network configuration.

[Explanation of symbols]

 10 Wireless Controller 11 Difference Calculation Logic 12 Delay Logic 14 Wired Transmission Line of High Speed Digital Network

Claims (1)

[Claims] 1. A mobile station comprising a plurality of radio base stations, wherein each of the base stations is connected to a plurality of mobile stations via a time division multiplexing radio line, and each base station is a mobile line for synchronizing frame timing by a wired line. In the communication system, the difference between the system frame signal generated from the system reference clock supplied from the wired circuit and the wireless frame signal received from another base station is converted into a count number of the system reference clock by a difference calculation logic, A method for correcting an inter-base station synchronization signal, characterized in that a delay logic corrects a system frame signal generated from a system reference clock according to a converted value.