JP2731640B2 - TDMA frame synchronization method between multiple radio base stations - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TDMA (Time Division Multiple Access) type digital mobile communication system in which a plurality of service areas are provided and a radio base station is arranged for each of the service areas, and in particular, synchronization between radio base stations. About the method.

[0002]

2. Description of the Related Art Generally, in this type of TDMA digital mobile communication system, as shown in FIG. 2, radio base stations 20a and 20b are arranged for each of a plurality of service areas 25a and 25b, and radio base stations 20a and 20b are arranged.
Are connected to the control station 10. The mobile station 30 communicates with the control station 10 using a time slot allocated via a radio base station in a service area where the mobile station 30 is located, for example, the radio base station 20a.

[0003] Incidentally, the mobile station 30 is located in the service area 25.
When the mobile station moves from a to the service area 25b (moving between service areas is referred to as handover), the mobile station communicates with the control station 10 via the radio base station 20b.

[0004] Next, at the time of handover, as shown in FIG. 4, TDM is performed between the radio base station 20a and the radio base station 20b.
If the A frame is not synchronized, the mobile station 30
Needs to start communication after synchronizing the TDMA frame with the radio base station 20b after the handover. For this reason, as shown in FIG.
In order to synchronize the TDMA frame of 0b, it is necessary to simultaneously reset the TDMA frame generators of the radio base stations 20a and 20b.

As a method for simultaneously resetting a plurality of TDMA frame generators, it has been proposed to transmit a reset signal to each of the radio base stations 20a and 20b via an artificial satellite 60 as shown in FIG. I have. This reset signal is received via the antennas 70a and 70b of each radio base station 20a and 20b, thereby resetting the TDMA frame generator of each radio base station 20a and 20b and synchronizing the TDMA frame of each base station. Take.

[0006]

As described above, the TDM
In the A-type digital mobile communication system, when synchronizing between radio base stations, it is proposed to use an artificial satellite, but the system becomes large-scale and is not practical.

Conventionally, without increasing the size of the system,
Synchronization between radio base stations has not been proposed, and therefore, synchronization between radio base stations may not be obtained. When a mobile station performs handover, the radio base station after the handover is re-started. Synchronization will be performed. For this reason, the sound is interrupted at the time of handover.

Accordingly, an object of the present invention is to provide a TDM system in which voice is not interrupted when a mobile station performs handover.
A method is to provide a synchronization method between radio base stations in a digital mobile communication system.

[0009]

According to the present invention, a radio base station having a TDMA frame generator is arranged for each of a plurality of service areas, and a time slot to which a mobile station moving in the service area is assigned is used. A TDMA type digital mobile communication system for transmitting and receiving a digital signal to and from a radio base station in a service area where the mobile station is located, a synchronization signal generating means for generating a reset pulse for resetting the TDMA frame generator; A delay unit having a delay amount set in accordance with a positional relationship between the synchronization signal generation unit and the radio base station, wherein the reset signal is provided to the TDMA frame generator via the delay unit. And the radio
A base station, wherein the synchronization signal generation means and the radio base station
To measure the amount of delay on the transmission path according to the positional relationship,
Via the delay means in the direction of the synchronization signal generation means
Sampling pulse which sends out sampling pulse without
Generating means, wherein the synchronizing signal generating means includes the sump.
Receiving a ring pulse and returning directly to the radio base station
Folding means for folding back as a pulse, and
The radio base station detects the reception time at which the return pulse was received.
The sampling pulse transmission time and the reception time
Determining the delay amount based on the time determined by
A TDMA frame synchronization method between a plurality of radio base stations, characterized in that a stage is provided, is obtained.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention.

Referring to FIG. 1, in one embodiment of the present invention, first and second service areas 25a and 25a
5b includes first and second radio base stations 20a, respectively.
And 20b are arranged. The first and second wireless base stations 20a and 20b are connected to the control station 10 via a communication cable or the like. When located in the first service area 25a, the mobile station 30 performs digital communication with the control station 10 via the radio base station 25a using the assigned time slot. Similarly, when the mobile station 30 is located in the second service area 25b, the mobile station 30 performs digital communication with the control station 10 via the radio base station 20b.

In this embodiment, the synchronization signal generator 4
0 and the first and second radio base stations 20a and 20b
And second delay amount measuring devices 50a and 50b, and first and second delay amount adjusting devices 55a
And 55b. Synchronous signal generator 4
0 is the first and second delay adjusting devices 55a and 55
b, it is connected to the first and second wireless base stations 20a and 20b. The first and second delay amount measuring devices 50a and 50b have first and second pulse generators 51a and 51b, respectively, and first and second delay processors 52a and 52b.

The first pulse generator 51a sends out a sampling pulse when the system of the first radio base station 20a starts up. A feedback circuit is configured between the first and second wireless base stations 20a and 20b and the pulse signal feedback device 41. This transmission pulse is transmitted as a return pulse in the pulse signal feedback device 41. The first delay processor 52a detects the return pulse, obtains a time ta from sending the sampling pulse to detecting the return pulse, and calculates the time ta between the control station 10 and the first wireless base station from the time ta. The amount of delay on the transmission path by the cable is calculated. From this delay amount, a first set delay amount to be set in the first delay adjusting device 55a is calculated. Similarly, when the system of the second radio base station 50b starts up, the second delay amount measuring device 50b sends out a sampling pulse and detects a return pulse to determine the amount of delay on the transmission path. The second set delay amount to be set in the delay adjusting device 55b is calculated.

Next, a method of obtaining the delay amount will be described with reference to FIG. If the maximum delay amount is T, the set delay amount set in the first delay adjustment device 55a is (T-ta
/ 2).

Each of the first and second delay adjusting devices 55a and 55b, to which the first and second set delay amounts are set, has a signal delay unit. After the TDMA frame from which the generator 40 has transmitted the reset pulse, the first and second TDMA frame generators 21a and 22b are reset at the same timing.

Using the principle described above, it is possible to synchronize TDMA frames transmitted from all the radio base stations connected to one control station.

[0017]

As described above, according to the present invention, the delay adjusting device is installed in each radio base station, and the transmission pulse transmitted from the synchronizing signal generator is transmitted by the delay adjusting device to the delay of each radio base station. Because it is delayed by the amount
With a simple configuration, each radio base station can simultaneously reset the TDMA frame generator without increasing the load on the control station . As a result, the TDMA frame can be synchronized between the radio base stations. Even if the mobile station moves between service areas, it is not necessary to re-frame the radio base stations at the time of handover. Not only can handover be performed, but there is no signal interruption.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a positional relationship between a control station and a radio base station.

FIG. 3 is a diagram for explaining a conventional radio base station synchronization method.

FIG. 4 is a diagram illustrating a timing relationship of a TDMA frame transmitted from an adjacent wireless base station.

FIG. 5 is a diagram illustrating a timing relationship of a TDMA frame transmitted from an adjacent wireless base station.

FIG. 6 is a diagram for explaining how a delay amount adjusting device determines a delay amount in the embodiment shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Control station 20a, 20b Radio base station 25a, 25b Service area 30 Mobile station 40 Synchronous signal generator 41 Pulse signal feedback device 50a, 50b Delay amount measuring device 51a, 51b Delay measuring pulse generator 52a, 52b Delay amount processor 55a , 55b Delay adjustment device 60 Artificial satellite

Claims (1)

(57) [Claims] 1. A radio base station having a TDMA frame generator is arranged for each of a plurality of service areas, and a mobile station that moves in the service area is assigned a time slot assigned to the mobile station. TDMA for exchanging digital signals with radio base stations
Synchronous signal generating means for generating a reset pulse for resetting the TDMA frame generator, and a delay in which a delay amount is set according to a positional relationship between the synchronous signal generating means and the radio base station. Means for resetting said TDMA signal via said delay means.
Together so that given frame generator, the radio base station, the wireless base and the synchronizing signal generating means
Measures the amount of delay on the transmission line according to the positional relationship with the base station
Through the delay means in the direction of the synchronization signal generating means.
Sampler that sends out sampling pulses without performing
Means for receiving the sampling pulse.
And return as it is in the direction of the radio base station as a return pulse.
The wireless base station has a receiving time at which the return pulse is received.
Detecting the sampling pulse transmission time and the reception
The decision to determine the delay amount based on the time determined by the time
TDMA frame synchronization scheme between a plurality of radio base stations, characterized in that a constant means.