JPH05308333A - Frame synchronization system of tdma system radio base station - Google Patents

Abstract

PURPOSE:To remove interference without extending line facilities by generating TDMA frame timing at a main base station of plural radio base stations, making other slave base stations monitor it, and performing subordinate synchronization. CONSTITUTION:A line control station 1 repeats a digital signal between a pay telephone line or PBX and a radio base station 2 to supply a TDMA transmission clock timing signal in a radio section to the base station 2. In this state, the base station 2-1 serves as the main station to generate the TDMA frame timing autonomously. Other base stations 2-2-2-m as slave stations monitors the frame timing from the master station and performs the frame synchronism by using data for the synchronization which consists of a specific bit array from the main base station 2-l. Consequently, transmission and reception by TDMA can be performed among the base stations without providing a control line for frame synchronization and a radio communication can be made in the same frequency band without interference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to TDMA (Time Div).
ison Multiple Access: Time-division multiple access) system The present invention relates to a frame synchronization system between a plurality of radio base stations in digital mobile communication.

[0002]

2. Description of the Related Art Mobile radio systems, particularly mobile telephone systems for public communication such as car telephones, radio calls, and cordless telephones, have rapidly spread, and digitization has been advanced in order to effectively utilize valuable frequency resources. ing. The current analog type car telephone system is a mobile base station, a radio base station for exchanging signals with the mobile base station,
It is composed of a car telephone exchange station having an interconnection function between a fixed telephone network and a radio base station or a line control station, and a radio line control station for controlling from the exchange station to the mobile station. The digitization of such a system means that the signal transmission format of a wireless transmission line between a mobile station, that is, an automobile or a mobile telephone or a mobile telephone carried by a human and a radio base station that exchanges radio waves with them is analog. It means changing from frequency modulation to digital modulation. The TDMA system is an example of the digital modulation, and is a system capable of accommodating a plurality of speech channels by temporally dividing one radio carrier wave. In this digital mobile communication, a synchronization technique for effectively allocating a plurality of communication channels randomly transmitted and received is one of the important techniques. FIG. 3 is a block diagram of a conventional system, and FIG. 4 is a time chart showing its transmission / reception timing. In FIG. 3, 11 is a line control station, 12 is a plurality (m) of radio base stations, and 13, 14 and 15 are mobile stations within the service areas of the respective radio base stations (12-1) to (12 to m). is there. FIG. 4 is a time chart when the two radio base stations 12-1 and 12-2 of FIG. 3 are transmitting / receiving with a plurality of mobile stations.

[0003]

In the conventional method shown in FIGS. 3 and 4, the radio base stations 12-1 to 12-m operate independently because their frame timings are asynchronous with each other. When transmitting and receiving with the mobile station, interference occurs because one base station 12-1 is in the receiving state and the other base station 12-2 is in the transmitting state in the sections A, B, and C of FIG.
Therefore, time division multiple access cannot be performed in the same frequency band, and each radio base station searches for a frequency band that is not used by another base station, selects a different frequency, and transmits. This is a problem in effective use of frequency. To solve this problem, means for distributing a reference signal for frame timing control from the line control station 11 to each of the radio base stations 12-1 to 12-m to ensure frame synchronization of all base stations. There is. However, in order to carry out this means, it is necessary to provide the reference signal line 16 as shown by the broken line in FIG. 3, and there is a drawback that the construction cost and equipment cost increase and an economic problem occurs. An object of the present invention is to solve the problem of the prior art, that is, increase in equipment cost associated with frame synchronization between a plurality of base stations, and to enable transmission / reception in the same frequency band without interfering with each other. It is to provide a frame synchronization method for a base station.

[0004]

A frame synchronization system for a TDMA wireless base station according to the present invention eliminates interference between a plurality of distributed wireless base stations connected to a line control station of TDMA digital mobile communication. In order to avoid, a TDMA transmission clock timing signal of a wireless section between each of the plurality of wireless base stations and a mobile station wirelessly connected is supplied from the circuit control station to the plurality of wireless base stations, One of the plurality of radio base stations is a master base station and the other radio base station is a slave base station, and a predetermined TDMA frame timing signal is generated and transmitted from the master base station, and the slave base station is the master base station. It is characterized in that the frame timing signal from the station is monitored to establish slave synchronization.

[0005]

1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a line control station, 2 is a plurality (m) of radio base stations, 3, 4 and 5 are radio base stations (2-1) to (2).
-M) indicates a mobile station within the service area. FIG. 2 is a time chart for explaining the operation of the present invention, showing the synchronization timing between the two base stations 2-1 and 2-2. In the block diagram of FIG. 1, the line control station 1 is a public line or P
The digital signal between the BX and the radio base stations 2-1 to 2-m is relayed, and the TDMA transmission clock timing signal in the radio section is supplied to each base station. In this state, the base station 2-
1 as a main station autonomously performs TDMA frame timing generation. The other base stations 2-2 to 2-m, which are slave stations, monitor the TDMA frame timing from the main base station 2-1 and use the synchronization data composed of the specific bit array from the main base station 2-1 to create a frame. Synchronize. Also, in order to avoid loss of frame synchronization due to the occurrence of a failure at the same timing, the main base station uses an idle reception slot to inspect for the presence of radio waves from other base stations, and if there is, a frame It is judged to be out of synchronization, and the frame of the slave base station is resynchronized. When there is no radio wave, it is determined that frame synchronization is in progress and frame resynchronization is not applied. As in the example of the synchronization timing between the base stations shown in FIG.
After the power is turned on, 1 autonomously generates TDMA frame timing as a master station. Other base stations 2-2 to 2-m
As a slave station, it enters the reception mode at the initial stage of power-on and monitors the synchronization data from the main base station 2-1. If it can be detected, TDMA is performed in synchronization with the corresponding frame timing.
Generates frame timing. As a result, FIG.
It is possible to perform TDMA transmission / reception between a plurality of base stations without providing the frame synchronization control line 16, and wireless communication can be performed without interference in the same frequency band. For example, when the line connecting the line control device and the base station is an ISDN line such as INS net 64 (2B + D), the 192 kHz lines of the ISDN line operate independently of each other, but the present invention is implemented. By doing
The line can be used as it is without adding a control line for frame synchronization for synchronizing each line.

[0006]

As described above, by carrying out the present invention, there is an advantage that the problem of effective use of frequency can be solved and an increase in equipment cost due to frame synchronization can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing synchronization timing between base stations of the present invention.

FIG. 3 is a block diagram of a conventional system.

FIG. 4 is a time chart showing a transmission / reception timing of a conventional technique.

[Explanation of symbols]

 1 line control station 2 radio base station 3,4,5 mobile station 11 line control station 12 radio base station 13,14,15 mobile station 16 frame synchronization signal line

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location H04Q 11/04 304 B 9076-5K (72) Inventor Shunichi Wakamatsu 2-3 Toranomon, Minato-ku, Tokyo No. 13 Kokusai Electric Co., Ltd. (72) Inventor Shinichi Kato 2-3-3 Toranomon, Minato-ku, Tokyo Kokusai Denki Co., Ltd.

Claims (2)

[Claims] 1. In order to avoid interference between a plurality of distributed radio base stations connected to a line control station of TDMA digital mobile communication, the line control station sends the plurality of radio base stations to the plurality of radio base stations. To supply a TDMA transmission clock timing signal in a wireless section between each of the plurality of wireless base stations and a mobile station wirelessly connected, and use one of the plurality of wireless base stations as a main base station. The wireless base station is used as a slave base station to transmit a predetermined TD from the master base station.
A TDM in which an MA frame timing signal is generated and transmitted, and the slave base station monitors the frame timing signal from the master base station to establish slave synchronization.
A system Frame synchronization system for wireless base stations. 2. The frame synchronization method for a TDMA wireless base station according to claim 1, wherein the main base station uses an idle reception slot in order to cope with a loss of frame synchronization caused by a failure or the like. 2. The TDMA wireless base station according to claim 1, wherein the slave base station is inspected for the presence of a transmission radio wave, and when the transmission radio wave is present, the slave base station is resynchronized. Frame synchronization method.