JPH05308334A - Frame synchronization system of tdma system radio base station - Google Patents

Abstract

PURPOSE:To remove interference without extending facilities by performing subordinate synchronization when synchronism data from other base stations is detected in a constant period at the time of the initialization of a radio base station or generating frame timing when not. CONSTITUTION:A line control station 1 repeats a digital signal between a pay telephone line or PBX and a radio base station 2 and supplies a TDMA transmission clock timing signal in a radio section to the base station 2. A base station 2-1 enters a reception mode at the time of power-ON initialization and detects synchronism data from other base stations 2-2-2-m for a constant period. When no synchronism data is detected in this period, the TDMA frame timing is autonomously generated, but when not, the TDMA frame timing in subordinate synchronism with the synchronism data is generated. Consequently, transmission and reception by TDMA among the base stations are enabled without extending circuit facilities and the interference is removed.

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. 5 is a block diagram of a conventional system, and FIG. 6 is a time chart showing its transmission / reception timing. In FIG. 5, 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. 6 is a time chart when the two radio base stations 12-1 and 12-2 of FIG. 5 are transmitting / receiving with a plurality of mobile stations.

[0003]

In the conventional method shown in FIGS. 5 and 6, the radio base stations 12-1 to 12-m operate independently because their frame timings are asynchronous with each other. When transmitting / 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 implement this means, it is necessary to provide the reference signal line 16 as shown by the broken line in FIG. 5, 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 avoids interference between a plurality of distributed wireless base stations connected to a line control station for TDMA digital mobile communication. In order to do so, the circuit control station supplies the plurality of radio base stations with a TDMA transmission clock timing signal in a radio section between each of the plurality of radio base stations and a mobile station wirelessly connected, When each of the plurality of radio base stations is set to a reception mode for a certain period at the time of initializing power-on to monitor a transmission wave from another radio base station and TDMA frame synchronization data is detected during the certain period. The present invention is characterized in that subordinate synchronization is set to the synchronization data, and TDMA frame synchronization data is independently generated when the synchronization data is not detected. Than it is.

[0005]

1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 1 is a line control station, which relays digital signals between a public line or PBX and radio base stations 2-1 to 2-m and supplies a TDMA transmission clock timing signal in a radio section to each base station. To do. 2 is a plurality (m) of radio base stations (2-1), (2-2), ... (2-m), and the line control station 1 and each of the radio base stations (2-1) to (2-).
m) Relays digital communication with mobile stations within the service area, and enters the reception mode at the initial of power-on (power ON) to detect the synchronization data from other base stations for a certain period. If synchronization data from another base station is not detected within this period, TDMA frame timing is autonomously generated, and if synchronization data from another base station is detected, the detected synchronization data is added. Dependently synchronized TDMA frame timing is generated. Three
Numerals 4 and 5 denote a plurality (n) of mobile stations within the service area of each base station, which communicate with each other by a wireless line based on frame synchronization of the base stations.

FIG. 2 is a flowchart showing the initial processing when the power of the base station is turned on. In the figure, 21
26 shows each step number. When the power of the base station is turned on (step 21), first the reception mode is entered to monitor the synchronization data from other base stations (step 22). Step 2 until monitoring starts and time is up after a certain period
Repeat step 3 → step 24 → step 22 to continue monitoring the synchronous data. If no synchronization data is detected during that time and a timeout occurs, the process proceeds from step 23 to step 26 to autonomously generate the TDMA frame timing. When it is detected, the process proceeds from step 24 to step 25, and the TD subordinately synchronized with the detected synchronization data is detected.
Generate MA frame timing.

FIG. 3 is a time chart showing an example of the synchronization timing of the two base stations 2-1 and 2-2. In FIG. 3, the base station 2-1 enters the reception mode at the time of power-on initial, detects synchronous data from another base station, but times out without being detected, and autonomously generates TDMA frame timing. Communication is performed with the mobile station using 1 transmission slot (1 transmission) and 1 reception slot (1 reception).
Similarly, the base station 2-2, which is turned on after the base station 2-1, enters the reception mode at the initial time and detects the synchronization data from other base stations. The synchronization data transmitted from the base station 2-1 is detected, and the TDMA frame timing subordinately synchronized with the synchronization data is generated according to the timing. In this way, the base stations 2-1 and 2-2 are brought into a frame synchronized state. By this method, not only the base station 2-2 but also a plurality of other base stations can establish frame synchronization with each other.

FIG. 4 is a transmission / reception timing chart of a plurality of base stations synchronized by the present invention. Assuming that the base station 2-1 communicates a transmission 1 slot and a reception 1 slot with a mobile station at a certain frequency, the base station 2-2 uses the transmission 2 slot and the reception 2 slot to communicate with the mobile station at the same frequency. Even if the base station 2-m communicates with the mobile station using the transmission m slot and the reception m slot, the base station 2-m can communicate with each other without interfering with each other. The slot used is an example. Also, in order to avoid the loss of frame synchronization due to the occurrence of a failure at the same timing, the base station uses an empty reception slot to check for the presence of radio waves from other base stations, and if there is, synchronize the frame. The frame is resynchronized by determining that it is out of sync. When there is no frame, it is determined that the frame is being synchronized, and the frame is not resynchronized. As mentioned above,
TDMA transmission / reception can be performed between a plurality of base stations without providing the frame synchronization control line 16 of FIG. 5, 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 so, it is possible to use the line as it is without adding a control line for frame synchronization for synchronizing each line.

[0009]

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 flowchart illustrating the operation of the present invention.

FIG. 3 is a time chart showing synchronization timing between base stations of the present invention.

FIG. 4 is a time chart of the base station of the present invention.

FIG. 5 is a block diagram of a conventional system.

FIG. 6 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 Matsuo Sato Matsuo 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 a plurality of radio base stations to the plurality of radio base stations. 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 to each other is supplied, and each of the plurality of wireless base stations receives a signal for a predetermined period at the time of initializing power-on. The mode is set, the transmission wave from another radio base station is monitored, and TDMA is performed during the certain period.
A frame synchronization method of a TDMA wireless base station, which is configured to establish dependent synchronization with the synchronization data when the frame synchronization data is detected, and to autonomously generate the TDMA frame synchronization data when the synchronization data is not detected. 2. The TDMA wireless base station frame synchronization method according to claim 1, wherein each of the plurality of wireless base stations receives an idle state in order to cope with a loss of frame synchronization caused by a failure or the like. 2. The frame of the TDMA wireless base station according to claim 1, wherein the presence or absence of a transmission wave of another radio base station is inspected using the slot, and resynchronization is applied when the transmission wave is present. Synchronous method.