JP2003009218A - Radio base station synchronization device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a PHS system from occurring interference by synchronizing control channel transmission from a plurality of radio base stations in which a channel for control shares channels of the same frequency. SOLUTION: A PHS radio base station detects the voltage peak of a commercial power source with a peak detecting part 4, reads a delay time from a memory 7 in which different delay times are set in each of radio base stations, and stats to transmit a control channel to the radio base stations using the same commercial power source after the delay time elapses from the peak detection.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio base station synchronization apparatus for synchronizing control channel transmission times from a plurality of radio base stations in a PHS system. is there. 2. Description of the Related Art FIG. 2 shows an example of a general asynchronous PHS data transfer system. In FIG. 2, there are n radio base stations such as PHS radio base stations CS1, CS2... CSn, and the terminal PS1 is located in the radio zone of the radio base station CS1.
There are three PHS terminals, namely, PS1, PS12 and PS13, and the terminals PS21 and PS2 are located in the wireless zone of the wireless base station CS2.
There are 2, PS23 and three PHS terminals. In the radio zone of the radio base station CSn, the terminals PSn1, PSn2,
There are PSn3 and three PHS terminals. Of course, the number of PHS terminals in the wireless zone of each wireless base station may be three or more, or three or less. Data terminals PC1, PC2,... PC constituted by personal computers
n is connected to the LAN line and performs data communication with the PHS terminal. Radio base stations CS1, CS2,... CSn
Are also connected to the same LAN line. Also, it is assumed that the power of the radio base stations CS1, CS2,... CSn uses the same commercial power of 100V. In the PHS data transfer system composed of a plurality of radio base stations shown in FIG. 2, each PHS terminal performs data communication with a data terminal connected to the same LAN via the radio base station. For example, data terminal PC1
In order for the PHS terminal PS11 to communicate, the radio base station CS1, CS2,..., CSn calls the PS11 using the radio control channel, and the radio base station CS1 responds to the PHS terminal PS11. Switching to the communication channel of the base station CS1 and communication between the PC1 and the PS11. The control channel used at this time is common to a plurality of radio base stations. That is, in FIG. 2, the radio base station CS1,
Control channels of the same frequency are used in CS2,... CSn. This is because the PHS terminal can be waiting on the same control channel regardless of the zone of any wireless base station. However, since PHS terminals are called using the same control channel, if the positions of the radio base stations CS1, CS2,. The problem that radio waves interfere with each other occurs. That is, when the radio base station CS1 and the radio base station CS2 are adjacent to each other, the radio waves of the radio base station CS1 are transmitted to the PHS terminals PS11 and PS1 in the zone of CS1.
2. It is natural that PS13 can receive, but PS21, PS22, PS2 in the zone of the radio base station CS2.
Even in the case of 3, the reception level is slightly lowered, but there may be a case where the signal can be received with a considerably high electric field strength. Therefore, for example, when the radio base station CS2 transmits the control channel in the same time zone as the radio base station CS1 transmitting the control channel, the radio waves of the radio base stations CS1 and CS2 interfere with each other and call And so on will not reach each PHS terminal. [0005] This mutual interference will be described with reference to FIGS. Each radio base station uses a control channel of the same frequency and intermittently transmits radio waves for a transmission time of T seconds. FIG. 3 is a diagram illustrating a case where the signals of the control channel are transmitted in synchronization with each of the radio base stations and there is no mutual interference. From the radio base station CS1, first, from time t0 to t1
The control channel is transmitted for an interval T seconds until the transmission interval, and then the radio wave is transmitted only for T seconds from time tn to t (n + 1). After the transmission of the radio base station CS1 stops, the radio base station CS2
The transmission is performed for T seconds from time t1 to t2, and the radio base station CS
3 is transmitted for the next T seconds from t2 to t3. As described above, if the transmission times are shifted so that the wireless base stations do not overlap with each other and the transmission is performed intermittently at the transmission period nT, no mutual interference occurs. However, if the transmission is performed asynchronously between the radio base stations without synchronization, the transmission radio waves of the radio base stations may overlap as shown in FIG. In FIG. 4, the transmission radio waves of the radio base stations CS1 and CS2 do not overlap, but the transmission of the radio wave of the radio base station CS3 starts between times t0 and t1, and stops transmission between times t1 and t2. Therefore, the radio waves of both the radio base stations CS1 and CS2 overlap. Since synchronization is not established between the radio base stations, transmission starts regardless of the transmission time of the other radio base stations. Therefore, it is difficult to avoid the overlap as shown in FIG. Synchronization may be achieved at each radio base station. However, there is no method for synchronizing between conventional PHS radio base stations, and there has been a problem of mutual interference of transmission radio waves. An object of the present invention is to provide a PHS system composed of asynchronous radio base stations as described above, achieve simple synchronization, realize transmission as shown in FIG. 3, and perform control between radio base stations. An object of the present invention is to provide a radio base station synchronizing apparatus in which overlapping of channel signals does not occur. [0007] In order to achieve the above object, the present invention provides a plurality of PHs using the same commercial power supply.
A radio base station synchronizer provided in each of the S radio base stations, wherein peak detection means for detecting a voltage peak time of the commercial power supply, and a delay time defined for each radio base station are stored. A memory, and control means for controlling to start control channel transmission of the radio base station when a delay time stored in the memory elapses from a time when the peak detection means detects a voltage peak of the commercial power supply. And a wireless base station synchronization device characterized by comprising: FIG. 1 is a block diagram of a radio base station provided with a synchronization device according to the present invention. The control unit 1 is a wireless unit 6
To communicate with the PHS terminal. Power supply circuit 3 is AC1
The power is received from a commercial power supply of 00 V, 50 Hz, converted into a required voltage, converted into a DC voltage by an AC / DC converter 2, and supplied to the control unit 1. The AC voltage of the power supply circuit 3 is sent to the peak detection unit 4 to detect the peak position of the 50 Hz AC voltage, and send the position to the control unit 1 as a pulse.
The timer 5 and the memory 7 are connected to the control unit 1. Since the commercial power supply is 50 Hz, the interval between the peak positions detected by the peak detection unit 4 is 20 ms. That is, 20 ms
Each time, a pulse waveform is added to the control unit 1 as an output of the peak detection unit 4. The control unit 1 receives the pulse from the peak detection unit 4 and knows the peak time of the commercial power supply. Hereinafter, the control unit 1 will be described with reference to the operation flow of FIG.
Will be described. The controller 1 checks whether a pulse from the peak detector 4 has arrived (NO in STEP 101). When a pulse comes (YES in STEP 101), the timer 5 is reset (STEP 102). That is, the value of the timer is set to 0. The timer 5 starts counting from the time when it is set to 0. The delay time given to the radio base station is stored in the memory 7 of the control unit 1. Assuming that four radio base stations are synchronized according to the present invention, the radio base station CS1 has a delay time of 0 ms, the radio base station CS2 has a delay time of 5 ms, and the radio base station CS3 has a delay time of 10 ms.
ms and 15 ms to the radio base station CS4. The controller 1 checks whether the value of the timer 5 has reached the delay time stored in the memory 7 (NO in STEP 103). In the case of the radio base station CS2, 5 ms is stored in the memory 7.
It is checked whether the timer 5 has reached 5 ms. If the delay time stored in the memory 7 has been reached (YES in STEP 103), the control unit 1 controls the radio unit 6 and performs control channel transmission for a determined time. In this system, one transmission time is set to 5 ms, so transmission is performed for 5 ms and necessary information is transmitted to the PHS terminal. When transmission is performed, the process returns to the beginning and waits again for a pulse from the peak detector 4 (STEP
101). [0010] Radio base stations CS1, CS2, CS3, CS
FIG. 5 shows a case where transmission is performed by synchronizing with four units 4.
Assuming that the peak detection time in the peak detection unit 4 is t0, this time is completely synchronized because the radio base stations CS1 to CS4 detect the peak of the same power supply. Then, the radio base station CS1 transmits for only 5 ms with a delay time of 0,
The radio base station CS2 takes a delay time of 5 ms and sets the time t0
Transmission is performed for 5 ms from the time of +5 ms. Radio base station C
At S3, the delay time is 10 ms, and the time t0 + 10m
5 ms from the time point s, and the radio base station CS4
With a delay time of 15 ms, transmission is performed for 5 ms from the time t0 + 15 ms. Since the next peak detection time in the peak detection unit 4 is t0 + 20 ms, from that point on, each of the radio base stations CS1, CS2, CS3, and CS4 sequentially transmits for 5 ms after a given delay time has elapsed. Do. In this way, each wireless base station can transmit the intermittent transmission for a transmission time of 5 ms every transmission cycle of 20 ms without overlapping the transmission radio waves of the wireless base station. That is, it is possible to easily synchronize each wireless base station using the commercial power supply. As is clear from FIG. 5, if the control channel transmission time from one radio base station is 5 ms, 50 Hz
When the power supply is used, the number of wireless base stations that can transmit without synchronizing transmission radio waves with each other is four. If a fifth wireless base station CS5 exists, this wireless base station CS5
5 are transmitted at the radio base stations CS1 and CS shown in FIG.
2, CS3, and CS4 always overlap with one of the transmission times. However, even if transmission times overlap, mutual interference of transmission radio waves does not occur if the distance between the two radio base stations is large. That is, mutual interference can be reduced by setting the transmission time of the radio base station CS5 to be the same as the transmission time of a radio base station that is not adjacent to the radio base station CS5. FIG. 7 shows an example of arrangement of wireless base stations. Radio base stations CS1, CS2, CS
3, CS4 and CS5 are arranged as shown in FIG. 7, the radio base station CS5 is a radio base station CS2 which is an adjacent radio base station.
And a transmission time different from CS4, for example, the radio base station CS1
May be transmitted at the transmission time. Since the radio base station CS2 is inserted between the radio base stations CS1 and CS5 transmitting at the same transmission time, mutual interference is reduced even when transmitting at the same time. In the case of a two-dimensional planar radio base station arrangement, if at least four non-overlapping transmission times can be taken, at least one radio base station is inserted between radio base stations having the same transmission time. Can be taken. Of course, with a one-dimensional linear wireless base station arrangement, a configuration in which three wireless base stations are interposed is possible. The frequency of the commercial power supply is 60H instead of 50Hz
In the case of z, the time interval for peak detection is 16.6 ms. Therefore, if one transmission time at the radio base station is 5 ms, transmission from four radio base stations can be prevented from overlapping. Absent. In three wireless base stations, the intermittent transmission cycle is 1
It becomes 6.6 ms. The transmission time of the fourth radio base station is the same as the transmission time of any of the three allocated radio base stations, but even if only three different transmission times are obtained,
A configuration is possible in which the transmission time of the fourth wireless base station is set to a transmission time different from that of the adjacent wireless base station. As described above in detail, the present invention makes it possible to perform synchronization between radio base stations of a PHS system, which has been difficult to transmit synchronously, by a simple method of synchronizing with the frequency of a commercial power supply. did. Because it is synchronized with commercial power,
It can be realized very economically. According to the present invention, the following effects can be obtained. (1) An economical inter-wireless base station synchronization device can be realized. (2) Arrangement of wireless base stations without mutual interference of control channels is facilitated. (3) Highly reliable communication with the PHS terminal is enabled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a radio base station provided with a synchronization device of the present invention. FIG. 2 is a configuration diagram of a data transfer system using a PHS system. FIG. 3 is an explanatory diagram of synchronous transmission in a plurality of radio base stations. FIG. 4 is an explanatory diagram of asynchronous transmission in a plurality of radio base stations. FIG. 5 is an explanatory diagram of synchronous transmission of power supply synchronization according to the present invention. FIG. 6 is an operation flow of the present invention. FIG. 7 is an example of arrangement of wireless base stations. [Description of Signs] 1 control unit 2 AC / DC converter 3 power supply circuit 4 peak detection unit 5 timer 6 radio unit 7 memory

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Claims (1)

Claims: 1. A plurality of PHSs using the same commercial power supply
Wireless base station synchronizer provided in each of the wireless base stations, comprising: peak detecting means for detecting a voltage peak time of the commercial power supply; and a memory storing a delay time defined for each wireless base station. And control means for controlling to start the control channel transmission of the radio base station when the delay time stored in the memory elapses from the time when the peak detection means detects the voltage peak of the commercial power supply. A radio base station synchronization apparatus characterized in that: