FRAME SYNCHRONIZATION SYSTEM BETWEEN BASE STATIONS OF MOBILE RADIO COMMUNICATION SYSTEM AND BASE STATION DEVICE EMPLOYING THIS SYSTEM

• US 20020012362A1
• Filed: 08/24/1998
• Published: 01/31/2002
• Est. Priority Date: 12/26/1996
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: MISHIMA, KATSUHIKO, YAHATA, HARUKI, TSUJIMURA, SATORU
• Granted Patent: US 6,480,483 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04B 7/269 Master/slave synchronisation

Abstract

An inter-base station frame synchronization system for use in a mobile communication system includes at least one master base station and a plurality of slave base stations. The master base station is provided with time information receiving means for receiving time information with high precision externally supplied, reference frame timing generation means for generating a reference frame timing on the basis of the time information, and first control channel signal transmission means for transmitting a control channel signal to the slave base stations in synchronism with the reference frame timing. Each of the slave base stations is provided with its own station frame timing generation means for generating an its own station frame timing on the basis of the reception timing of one of the control channel signals transmitted from the master base station and other slave base stations, and second control channel signal transmission means for transmitting a control channel signal in synchronism with the its own station frame timing.

Claims

1. An inter-base-station frame synchronous system in a mobile communication system comprising:

plural base stations dispersively arranged within a service area and connected to a communication network, and having at least one master base station and plural slave base stations; and

plural mobile stations wirelessly connected to said plural base stations by a time-division bidirectional multiplex system, wherein

said master base station comprises;

time information receiving means for receiving time information with high precision externally supplied;

reference frame timing generating means for generating reference frame timing for said time-division multiplex connection in synchronization with predetermined synchronous setting timing set on the basis of said time information; and

first control channel signal transmitting means for transmitting a control channel signal to said plural slave base stations located around its own station in synchronization with said reference frame timing, wherein

said slave base stations comprise;

control channel signal observation period setting means in which a predetermined period from a first receiving time point of a control channel signal transmitted from said master base station or other slave base stations during said frame synchronization control period is set to a control channel signal observation period;

its own station frame timing generating means for generating its own station frame timing on the basis of receiving timing of the control channel signal transmitted from said master base station or one of the other slave base stations when only this control channel signal is received during said control channel signal observation period set by said control channel signal observation period setting means, said its own station frame timing generating means also generating its own station frame timing on the basis of one of receiving timings of control channel signals respectively transmitted from said master base station or plural slave base stations among the other slave base stations when these control channel signals are received during said control channel signal observation period; and

second control channel signal transmitting means for transmitting each control channel signal in synchronization with said its own station frame timing after said control channel signal observation period is terminated.

2. The inter-base-station frame synchronous system of the mobile communication system according to claim 1, wherein the its own station frame timing generating means generates its own station frame timing in synchronization with the frame timing of a most advanced phase among plural frame timings based on the respective receiving timings of the control channel signals respectively transmitted from the master base station or plural slave base stations among the other slave base stations when these control channel signals are received during the control channel signal observation period.

3. The inter-base-station frame synchronous system of the mobile communication system according to claim 2, wherein, when the control channel signals respectively transmitted from the master base station or plural slave base stations among the other slave base stations are received, the frame timing of a most advanced phase among the plural frame timings based on the respective receiving timings of these control channel signals is discriminated as first frame timing within a period set at a frame interval from a time point shifted by a time about half this frame interval from a first receiving time point of the control channel signals during the control channel signal observation period.

4. The inter-base-station frame synchronous system of the mobile communication system according to claim 1, wherein the its own station frame timing generating means generates its own station frame timing based on receiving timing at a maximum receiving level among the control channel signals respectively transmitted from the master base station or plural slave base stations among the other slave base stations when these control channel signals are received during the control channel signal observation period.

5. The inter-base-station frame synchronous system of the mobile communication system according to any one of claims 1, 2, or 4, wherein, when the communication between base and mobile stations is approximately performed at the same time point as the beginning of the ordinary frame synchronization control period, the frame synchronous system further comprises frame synchronous starting extending means for setting a frame synchronous control period after the communication between base and mobile stations is terminated.

6. The inter-base-station frame synchronous system of the mobile communication system according to claim 5, wherein said second control channel signal transmitting means adds information showing whether the communication between base and mobile stations is performed or not or information showing whether it is suitable as reference of the frame synchronous control or not to the control channel signal.

7. The inter-base-station frame synchronous system of the mobile communication system according to claim 6, wherein said its own station frame timing generating means generates its own station frame timing based on the receiving timing of only a control channel signal to which information showing that the communication between base and mobile stations is performed or information prohibiting becoming to reference of the frame synchronous control, is not added.

8. The inter-base-station frame synchronous system of the mobile communication system according to any one of claims 1, 2, or 4, wherein the frame synchronous system further comprises talking connection request reception inhibiting means for inhibiting the reception of a talking connection request in at least a frame synchronous control period.

9. The inter-base-station frame synchronous system of the mobile communication system according to any one of claims 1, 2, or 4, wherein said second control channel signal transmitting means comprises:

control channel signal generating means for generating the control channel signal in synchronization with the frame timing of its own station; and

timing adjusting means for variably setting transmitting timing of the control channel signal generated by said control channel signal generating means on the basis of supposed delay information.

10. The inter-base-station frame synchronous system of the mobile communication system according to claim 9, wherein said timing adjusting means variably or fixedly sets said transmitting time such that a total time of a propagation delay time from a base station transmitting the control channel signal to its own station, a detecting time required from a receiving time point of this control channel signal to the detection of frame timing shown by this control channel signal, a generating time required from a detecting time point of this frame timing to the generation of its own station frame timing, and a transmitting time until the control channel signal is transmitted in synchronization with this generated its own station frame timing, is an substantially integer times a frame period.

11. The inter-base-station frame synchronous system of the mobile communication system according to claim 10, wherein said propagation delay time is fixedly set to zero or a predetermined value in each slave base station.

12. The inter-base-station frame synchronous system of the mobile communication system according to claim 10, wherein said timing adjusting means presumes the propagation delay time of the control channel signal used to generate its own station frame timing on the basis of a receiving level of the received control channel signal.

13. The inter-base-station frame synchronous system of the mobile communication system according to claim 12, wherein the transmitting level of the control channel signal is set to the same level in each of the master base station and the slave base stations.

14. The inter-base-station frame synchronous system of the mobile communication system according to claim 10, wherein said timing adjusting means presumes the propagation delay time of the control channel signal used to generate its own station frame timing on the basis of a receiving level of the received control channel signal and information showing a transmitting level transmitted from a base station on a transmitting side in this control channel signal.

15. The inter-base-station frame synchronous system of the mobile communication system according to claim 10, further comprising transmitting level information storing means for storing transmitting level information showing a transmitting level of the control channel signal in each of said plural base stations, wherein

in the received control channel signal used to generate its own station frame timing, said timing adjusting means judges the transmitting level of said received control channel signal with reference to the transmitting level information stored to said transmitting level information storing means on the basis of discriminating information of a base station on a transmitting side transmitted from the base station on the transmitting side in said control channel signal, and presumes the propagation delay time of this control channel signal from said transmitting level and the receiving level.

16. A base station apparatus dispersively arranged within a service area and used as a slave base station among plural base stations wirelessly connected to plural mobile stations by a time-division bidirectional multiplex system, the base station apparatus comprising:

control channel signal observation period setting means in which a predetermined period from a first receiving time point of a control channel signal transmitted from other base stations is set to a control channel signal observation period;

its own station frame timing generating means for generating its own station frame timing on the basis of receiving timing of the control channel signal transmitted from one of said other base stations when only this control channel signal is received during said control channel signal observation period, said its own station frame timing generating means also generating its own station frame timing on the basis of one of receiving timings of control channel signals respectively transmitted from plural base stations among said other base stations when these control channel signals are received during said control channel signal observation period; and

control channel signal transmitting means for transmitting each control channel signal in synchronization with said its own station frame timing after said control channel signal observation period is terminated.