JPH11205849A - Method for establishing inter-base station synchronizing timing and tdma system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish synchronization by a slave base station and to reduce the load of a master base station by changing various transmission timing, detecting the range of transmission timing, which can be received in the master base station and setting appropriate transmission timing by the slave base station. SOLUTION: A slave bases station 2 receives a frame signal from a master base station 1, demodulates it and synchronizes it with the transmission timing of a self-station in a synchronization part 25 so as to set it to an initial timing I. An inter-base station synchronization request signal is transmitted to the master base station 1 with the transmission timing I, timing obtained by advancing I by one clock and timing obtained by delaying I by one clock. The master base station 1 returns a response signal, when it is able to synchronize the signal to the synchronization request signal. The slave base station 2 determines the range of the fastest transmission timing and the slowest timing, when the response signal is received, to be the timing which can be synchronized, and sets the center value as the optimum transmission timing. Thus, a processing of the master base station can be relaxed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division multiplexing (TDMA) system having a plurality of base stations.
W using SON (Multiple Access)
LL (Wireless Local Loop) or PHS (Personal Handy Phone)
e System) relates to interference between base stations due to propagation delay of radio waves generated due to the distance between base stations.

[0002]

2. Description of the Related Art In a mobile communication system such as a PHS in which a plurality of base stations are provided and each base station transmits / receives to / from a mobile station by TDMA, frame transmission / reception signals of each base station can be synchronized. Otherwise, continuous time slots will be interfered by transmission / reception signals from adjacent base stations. For this reason, the wireless channel at that timing cannot be used, and effective use of radio waves cannot be achieved. Therefore, a master base station is selected from a plurality of base stations in order to synchronize a frame signal transmitted by each base station, and the remaining base stations are set as slave base stations, and the slave base station is set at the timing of the frame of the master base station. The timing of the stations is adjusted.

FIG. 8 is a diagram showing a synchronization relationship between the master base station and the slave base station. In the case of this example, the frame includes four slots (T1 to T4) of the transmission unit and four slots (R1 to R4) of the reception unit, and a guard bit is provided between each slot. In FIG. 8, 1
Is a master base station and 2 is a slave base station. FIG.
8A shows a transmission frame transmitted by the master base station 1 and a reception frame received by the slave base station 2, and FIG.
(B) shows that the slave base station 2 receives in the slot R1,
This is an example in which transmission data is embedded in a slot T1 and transmitted, and the master base station 1 receives the transmission data in a slot R1. In this case, since the distance between the base stations is short, the signal delay falls within the range of the guard bit, and no interference occurs between adjacent slots in the master base station 1.

However, when the distance between the base stations is large, the signal propagation delay does not fall within the range of the guard bit. FIGS. 8C and 8D show this example.
FIG. 8C shows that the slave base station 2 embeds the data in the slot T1 and transmits the data received in the slot R1 of FIG.
1 is an example of reception. As shown in the figure, the data of the slot R1 does not fit between the guard bits, but shifts to the next slot, and timing interference occurs in the master base station 1. FIG. 8D is an enlarged view of this relationship.

In order to solve this problem, Japanese Patent Laid-Open No. 9-1
In JP-A-48978, an attempt is made to solve the problem by a method of adjusting the amount of delay of the propagation time for each slave base station in the master base station based on the signal returned by the slave base station that has received the transmission signal from the master base station. I have.

[0006]

However, in the method disclosed in Japanese Patent Application Laid-Open No. 9-148978, the master base station must make adjustments to all slave base stations. When the number is increased, processing at the master base station becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is intended to provide a simple process for a slave base station to prevent interference between base stations caused by a distance between base stations. It is an object of the present invention to provide a method of obtaining appropriate transmission timing in a slave base station by adding the information and establishing synchronization between the base stations.

[0008]

A method for establishing synchronization timing between base stations according to the present invention has the following elements to obtain an appropriate transmission timing. (A) transmitting a synchronization request signal at a predetermined timing; (b) detecting a response signal to the synchronization request signal; (c) sequentially changing the transmission timing of the synchronization request signal; A step of obtaining a transmission timing range in which a response to the synchronization request signal can be obtained; and (e) a step of obtaining an appropriate transmission timing based on the obtained transmission timing range.

Further, the range of the transmission timing is obtained by advancing or delaying the predetermined timing by one clock.

[0010] Further, the appropriate transmission timing is set to be the center value of the range of the obtained transmission timing.

Further, the present invention has the following elements to obtain an appropriate transmission timing. (A) transmitting a synchronization request signal at a predetermined timing in the first base station; (b) receiving the synchronization request signal in the second base station; (c) the second base station Detecting a difference between the reception timing of receiving the synchronization request signal and its own optimal reception timing; and (d) transmitting the difference between the detected timings as a part of information of a response signal of the synchronization request signal. (E) detecting a response signal to the synchronization request signal in the first base station; and (f) determining an appropriate transmission timing based on the information in the response signal.

The present invention has the following elements so as to obtain an appropriate transmission timing. (A) obtaining distance data between base stations;
(B) registering the obtained distance data between base stations in a predetermined device; (c) transmitting the distance data from the predetermined device to each base station; (d) based on the distance data Calculating a data delay time between base stations; and (e) calculating an appropriate transmission timing based on the calculated delay time.

[0013] The present invention has the following elements so as to obtain appropriate transmission timing. (A) obtaining distance data between base stations;
(B) registering the obtained distance data between the base stations in a predetermined device; (c) transmitting the distance data from the predetermined device to a first base station; (d) a first base Transmitting the distance data from the station to the second base station; and (e) in the second base station, a data delay time between the first base station and the second base station based on the distance data. (E) calculating an appropriate transmission timing based on the calculated delay time in the second base station.

Further, the TDMA system is provided with any one of the above-described methods for establishing synchronization timing between base stations.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing a configuration of a part necessary for frame synchronization between a master base station and a slave base station according to Embodiment 1 of the present invention. In the drawing, reference numeral 1 denotes a master base station, a transmitting / receiving antenna 10, a transmitting unit 12 for transmitting a frame signal or the like to the transmitting / receiving antenna 10, or a receiving unit 1 for receiving a frame signal or the like
3, a CPU 14 (including a memory) for processing the entire master base station, a synchronizing unit 15 for synchronizing a received frame signal with its own timing, and a timing circuit 16 for outputting a frame signal. Have.

Reference numeral 2 denotes a slave base station, and a transmitting / receiving antenna 2
0, a high-frequency switch 21 for switching the transmitting / receiving antenna 20 to either a transmitting unit 22 for transmitting a frame signal or the like or a receiving unit 23 for receiving a frame signal or the like, a CPU 24 for performing processing of the entire master base station, and a signal obtained by receiving. Synchronizing section 2 for synchronizing the frame signal of the own station with the frame signal
6 is provided.

FIG. 2 is a diagram showing the concept of Embodiment 1 of the present invention. In FIG. 2A, 1 is a master base station, and 2, 3 and 4 are slave base stations. Each of the slave base stations 2, 3, and 4 transmits a request for synchronization between base stations to the master base station 1 using a control channel. By changing the timing of this transmission signal in various ways, FIG.
As shown in (b), the range of the receivable timing of the master base station 1 is obtained.

FIGS. 3 and 4 are flowcharts showing the detailed operation of slave base stations 2 to 4 in the first embodiment. The operation in the first embodiment will be described below with reference to the drawings.

The master base station 1 transmits the frame signal generated by the timing circuit 16 to the transmitting unit 1 in a predetermined slot.
2. Transmit via the high frequency switch 11. The slave base station 2 receives the frame signal from the master base station captured by the transmission / reception antenna 20 via the high frequency switch 21. The frame signal reproduced by the reception circuit 23 is synchronized by the synchronization circuit 25 with the transmission timing of the own station. The timing (initial setting timing) i at this time is defined as I (step S10).

At this transmission timing, the slave base station 2 transmits a request for synchronization between base stations to the master base station 1 via the transmission unit 22 and the high-frequency switch 21 (step S11). The slave base station 2 waits for a response from the master base station 1. The master base station 1 returns a response signal if the synchronization request signal from the slave base station 2 can be synchronized. Upon receiving this response, the slave base station 2 advances the transmission timing by one clock (step S13) and transmits a synchronization request (step S14). Thereafter, the slave base station 2
While the master base station 1 can respond, the operation of transmitting the synchronization request by advancing the transmission timing by one clock is repeated (steps S16 to S15), and the earliest transmission clock timing is detected and stored in the memory. (Step S17).

Next, the slave base station 2 transmits a synchronization request by delaying the initially set transmission timing I by one clock, and detects a transmission timing at which the master base station 1 can synchronize (steps S17 to S21). Are stored in a memory (step S2).
2).

Assuming that the earliest transmission timing is +2 clocks and the latest transmission timing is -4 clocks with respect to the initial setting transmission timing (i = I) obtained as described above, the optimum transmission timing Is (+ 2-4) with respect to the initial transmission timing (i = I).
/ 2 = −1, that is, a timing delayed by one clock from the initially set transmission timing. FIG. 5 illustrates this.

FIG. 4 shows an initial setting transmission timing (i =
I) is inappropriate and the master base station 1 cannot respond to the synchronization request from the slave base station 2 from the beginning (FIG. 3)
FIG. 9 is a flowchart diagram showing a process when the response reception is N in step S12). Hereinafter, description will be made with reference to this flowchart.

The transmission timing is advanced by one clock (step S30), and a synchronization request is transmitted (step S3).
1), and waits for a response from the master base station 1 (step S
32) If there is no response, the transmission timing is advanced by one clock (step S34), and it is determined whether the advanced clock number has reached a predetermined value (step S3).
3) If the value reaches a predetermined value, it is determined that it is useless to further advance the clock, and a synchronization request is transmitted at a timing one clock delayed from the initial setting timing (i = I) (step S35). ).

On the other hand, if the response from the master base station 1 can be received while the transmission timing is advanced by one clock, the value at that time is stored in the memory (step S50), It is regarded as the transmission timing. The transmission timing is further advanced to detect the earliest transmission timing (steps S51 to S51).
53), and stores this value in the memory (step S5).
4). Through the above processing, an optimal transmission timing can be obtained.

When a response from the master base station is not obtained even if the transmission timing is advanced, the transmission timing is delayed by one clock from the initial setting as described above (step S35), and the synchronization request is transmitted (step S35). S3
6) Then, it waits for a response from the master base station 1 (step S37). If there is no response, the transmission timing is further delayed by one clock (step S39). If there is no response even if it is delayed until a predetermined timing (step S39) (Step S38), synchronization is impossible (step S40), and an alarm is issued (step S41).

On the other hand, when a response is obtained at a certain timing, the value at that time is stored in the memory (step S60), and this is regarded as the earliest transmission timing. By further delaying the transmission timing, the latest transmission timing is detected (step S61 to step S61).
63), and stores this value in the memory (step S6).
4). Through the above processing, an optimal transmission timing can be obtained.

In the above-described embodiment, the transmission request is transmitted by changing the transmission timing by one clock. However, the present invention is not limited to this method. You may make it do. Alternatively, the initially set direction in which the transmission timing is advanced and the direction in which the transmission timing is delayed may be alternately performed. Further, when the range of the transmission timing is wide, it is not always necessary to set the transmission timing to the median value between the latest transmission timing and the latest transmission timing.

As described above, according to the first embodiment, an appropriate transmission timing can be obtained by the processing of only the slave base station.

Embodiment 2 FIG. FIG. 6 is a flowchart illustrating the operation of the master base station and the slave base stations according to the second embodiment. Hereinafter, the operation will be described with reference to FIGS. Master base station 1 has timing circuit 1
The frame signal generated in step 6 is transmitted via the transmission unit 12 and the high-frequency switch 11 in a predetermined slot. The slave base station 2 receives the frame signal from the master base station captured by the transmission / reception antenna 20 via the high frequency switch 21. The frame signal reproduced by the reception circuit 23 is synchronized by the synchronization circuit 25 with the transmission timing of the own station. The timing (initial setting timing) i at this time is defined as I (step S70). The master base station 1 calculates the optimum value of its own reception timing by the CPU 14 based on the frame counter, and stores the calculated value in the memory (step S80).

At this transmission timing, the slave base station 2 transmits a request for synchronization between base stations to the master base station 1 via the transmission unit 22 and the high-frequency switch 21 (step S71). The slave base station 2 waits for a response from the master base station 1. When receiving the synchronization request signal from the slave base station 2 (step S81), the master base station 1 obtains the difference between the reception timing and the optimum reception timing stored in the memory by the number of clocks (step S8).
2). This value is defined as T. The difference T between the obtained reception timings
Is embedded as information in the response signal to the slave base station 2 and the response signal is transmitted (step S83). When receiving the response signal, the slave base station 2 extracts the reception timing difference data T of the master base station 1 embedded in the response signal (step S72), and determines the transmission timing based on the data (I + T). ) (Step S73).

As described above, according to the second embodiment, the optimum transmission timing can be set by a simple process.

Embodiment 3 FIG. 7 is a diagram showing another embodiment of the present invention. In the figure, 1 is a master base station, 2, 3 and 4 are slave base stations, and 5 is a control device for controlling the master base station 1. In the second embodiment, since the installation position of each base station is known, the propagation delay time of the signal is calculated by utilizing the fact that the distance between each base station can be calculated in advance, and the optimum transmission is performed. It is to get the timing.

The master base station 1 and the slave base station 2,
The distances to 3 and 4 are d1, d2 and d3, respectively. The distance between the slave base station 2 and the slave base station 3, the distance between the slave base station 2 and the slave base station 4, and the distance between the slave base station 4 and the slave base station 2 are d12, respectively. , D13 and d23.

The above distance data between the base stations is registered in the control device 5, and this data is transmitted to each base station at the time of initial setting. That is, the control device 5 transmits d1, d2, and d3 to the master base station 1, d1, d12, and d31 to the slave base station 2, and d1, d12, and d31 to the slave base station 3.
2, d12, d23, and d3, d to the slave base station 4.
23, d31. Each slave base station 2, 3, 4
Then, the signal propagation delay time is calculated and obtained by the CPU.
That is, the distance to the received master base station 1 is obtained by dividing the distance by the propagation speed of the radio wave. Then, an appropriate transmission timing is obtained from the obtained delay time.

As described above, in the third embodiment, an appropriate transmission timing can be easily calculated only by the slave base station. In addition, since distance data between related base stations is transmitted to all base stations, processing such as when the master base station goes down or switching between the master base station and the slave base station is facilitated. Can be done. Further, the wireless procedure between the master base station and the slave base station in the initial setting can be simplified.

Embodiment 4 FIG. The fourth embodiment is a modification of the third embodiment. In the fourth embodiment, the distance between each base station is transmitted from the control device to each base station, and distance data between the base station and another base station is transmitted. All data relating to the distance between base stations is transmitted to the master base station 1, and the master base station 1 distributes and transmits this data to the respective slave base stations 2 to 4. Even in this case, the same effect as in the third embodiment can be obtained.

[0038]

As described above, according to the present invention, the transmission timing is variously changed to detect the range of transmission timing receivable by the master base station, so that an appropriate transmission timing is set. be able to.

Since the transmission timing is changed one clock at a time to detect whether or not the signal can be received by the master base station, a detection program can be created with simple logic.

Further, the median of the range of the detected transmission timing is set as the transmission timing.
Optimal transmission timing can be obtained.

Since the master base station notifies the slave base station of the difference between the optimum value of its own reception timing and the received reception timing, an appropriate transmission timing in the slave base station can be easily set. be able to.

Further, the distance data between the base stations is collectively managed by the control device, and this data is transmitted to each base station, so that the signal propagation delay time can be easily calculated. Appropriate transmission timing can be set. Further, it becomes easy to set the master base station to another base station.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of related hardware portions according to a first embodiment.

FIG. 2 is a diagram illustrating the concept of the first embodiment.

FIG. 3 is a flowchart showing an operation according to the first embodiment.

FIG. 4 is a flowchart showing an operation in the first embodiment.

FIG. 5 is a diagram showing an example of setting an appropriate transmission timing according to the first embodiment.

FIG. 6 is a flowchart illustrating the operation of the second embodiment.

FIG. 7 is a diagram illustrating Embodiment Modes 3 and 4;

FIG. 8 is a diagram for explaining conventional slot interference.

[Explanation of symbols]

1 Master base station, 2, 3, 4 Slave base station, 5
Control device, 10, 20 transmitting / receiving antenna, 11, 21
High frequency switch, 12, 22 Transmitter, 13, 23
Receiving unit, 14, 24 CPU, 15, 25 Synchronizing unit, 1
6 Timing circuit.

Claims (7)

[Claims] 1. A method for establishing synchronization timing between base stations having the following elements: (a) transmitting a synchronization request signal at a predetermined timing; (b) detecting a response signal to the synchronization request signal; ) A step of sequentially changing the transmission timing of the synchronization request signal; (d) a step of determining a transmission timing range in which a response to the synchronization request signal is obtained; and (e) an appropriate transmission timing based on the determined transmission timing range. Step for seeking. 2. The method according to claim 1, wherein the range of the transmission timing is obtained by advancing or delaying the predetermined timing by one clock. 3. The method for establishing synchronization timing between base stations according to claim 1, wherein the appropriate transmission timing is a median of a range of the determined transmission timing. 4. A method for establishing synchronization timing between base stations having the following elements: (a) transmitting a synchronization request signal at a predetermined timing in a first base station; and (b) transmitting a synchronization request signal in a second base station. Receiving the synchronization request signal; (c) detecting, at the second base station, a difference between the reception timing at which the synchronization request signal was received and its own optimal reception timing; Transmitting the difference as a part of the information of the response signal of the synchronization request signal; (e) detecting a response signal to the synchronization request signal in the first base station; Determining an appropriate transmission timing based on the above information. 5. A method for establishing synchronization timing between base stations having the following elements: (a) obtaining distance data between base stations; and (b) registering the obtained distance data between base stations in a predetermined device. (C) transmitting the distance data from the predetermined device to each base station; (d)
Calculating a data delay time between the base stations based on the distance data; and (e) calculating an appropriate transmission timing based on the calculated delay time. 6. A method for establishing synchronization timing between base stations having the following elements: (a) obtaining distance data between base stations; and (b) registering the obtained distance data between base stations in a predetermined device. (C) transmitting the distance data from the predetermined device to a first base station;
(D) transmitting the distance data from the first base station to the second base station; (e) in the second base station, a first base station and a second base station based on the distance data (E) calculating an appropriate transmission timing in the second base station based on the calculated delay time. 7. A TDM provided with the method for establishing synchronization timing between base stations according to any one of claims 1 to 6.
A system.