JPH03210836A - Receiver for phase synchronization - Google Patents

Abstract

PURPOSE:To realize a receiver for phase synchronization with a wide dynamic range with economy by using a control signal from a decoder needed substantially so as to control the attenuation of an attenuator provided to the receiver. CONSTITUTION:In the case of phase synchronization, a radio wave of a station around its own station is stopped in a prescribed time alpha seconds after a specific signal A included in the radio wave from the station around its own station is received and a weak radio wave of a reference station is received. When a radio wave of the station around its own station is received, an attenuator is operated when a received voltage reaches almost a standard reception voltage and at a lapse of a seconds after the special signal A for phase adjustment is detected by a decoding circuit of a receiver, the attenuation of an attenuator 10a is decreased in the timing stopping the transmission of the radio wave of the station around its own station and a level of the voltage by a radio wabe from the reference station is received by the standard voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a phase synchronization radio receiver necessary for simultaneous multi-station transmission in a mobile communication system.

(Prior art) In mobile communication systems, when covering a wide area using multiple small wireless zones, there is a method in which radio waves of the same frequency are simultaneously transmitted from multiple wireless base stations installed in each small wireless zone. be. This is called simultaneous multi-station transmission, and is used in radio paging systems, car telephone systems, etc. This is reference 1 (Fundamentals of Mobile Communications, published by the Institute of Electronics, Information and Communication Engineers)
Section 7.4, pages 180 to 185).

At this time, transmission quality improves due to the diversity effect at a location where the distance from multiple wireless base stations, that is, the strength of the received radio waves is approximately equal, but the phase shift of the signals sent from each wireless base station becomes large (and , on the contrary, the transmission quality deteriorates. Therefore, when performing multi-station simultaneous transmission, it is essential to synchronize the phase of the signals transmitted from each base station. For example, in the radio paging system, the transmitted signal is the signal from the switching center. is transmitted from each wireless base station via the station that transmits the signal (hereinafter referred to as the "central station"), but in order to achieve phase synchronization, the delay time of the transmission path between this central station and each base station must be measured. However, it is necessary to adjust the signal delay so that the delay time is the same for all wireless base stations.This situation is shown in Figures 2 and 3.
As shown in the figure. FIG. 2 shows the line configuration of the radio paging system, and FIG. 3 shows the configuration of the base station.

As shown in Figure 2, the delay adjustment method involves transmitting the same signal from a central station to multiple base stations, and transmitting the same signal to a reference radio base station (hereinafter referred to as the "reference station") that is modulated by that signal. ) is received by other wireless base stations (hereinafter referred to as "peripheral stations"), the phase is compared with the signal sent from the central station via the wired transmission path, and the base station A common method is to adjust the variable delay circuit of the station. In Figure 2, in the case of peripheral stations that cannot directly receive the radio waves of the reference station, the phase of many base stations can be adjusted by repeatedly adjusting the variable delay circuit using the peripheral station with the same phase as the reference station as the reference station. Can be matched. The details are described in Document 2 ("Car Telephone", Section 7.5, pages 150 to 152, published by the Institute of Electronics, Information and Communication Engineers).

In this case, since the delay can be adjusted using the delay circuit in the peripheral station, the delay time between the central station and the reference station is larger than the delay time between the central station and other peripheral stations. It is necessary to insert a fixed delay circuit between the central station and the reference station.

The configuration of the base station required for this purpose is shown in FIG. 4(a).

However, in this configuration, since the variable delay circuit is provided in front of the transmitter, it is not possible to eliminate transmission phase errors due to variations in delay time of the transmitter of the base station.

To eliminate this, each base station also receives radio waves transmitted by itself and adjusts the delay to synchronize with the signal from the reference station. This is shown in FIG. 4(b), and the details are described in the above document 2.

FIG. 4 shows the configuration of this conventional delay adjustment system and the signal transmission method.

Figure 4(a) is an example of a configuration in which the reception voltage of the reference station and the reception voltage of the peripheral station in the receiver installed in the peripheral station are the same even if the same antenna is used for reception, and the reception voltage from the antenna is the same. Radio waves are received by one receiver, each radio wave is demodulated, and the delay time difference is measured by comparing the phase difference between the signals of each base station. At this time, since the frequencies of the received radio waves are the same, as shown in Figure 4(c), while receiving the radio waves from the reference station, the radio waves from the surrounding stations are stopped and inserted into the signal. time difference between special signals (from receiving special signal A to special signal B)
By measuring the difference in time until the signal is received, the difference in time between local inspections of the transmission path can be measured isometrically. In addition, as a method to stop the radio waves of the peripheral station, by setting the time difference between special signal A and special signal B as a fixed time interval, the peripheral station demodulates and decodes the radio waves sent from its own peripheral station and transmits the special signal. This can be easily achieved by stopping the radio waves of the surrounding station α seconds after detecting the signal A, and starting transmitting the radio waves after receiving the special signal B.

Further, the time difference (α-β) between the time difference β and α between receiving the special signal A and receiving the special signal B becomes a phase error.

Time can be measured by methods such as obtaining a signal at constant time intervals by frequency-dividing the lock required for decoding the signal, or counting the number of periodic pulses in the decoded signal.

(Problem to be Solved by the Invention) However, if there is a difference between the reception voltage of the reference station and the reception voltage of the peripheral station in the receiver installed at the peripheral station, it is necessary to make the sensitivity of the receiver different. As shown in FIG. 3(b), it becomes necessary to provide a receiving antenna and a receiver for each transmitting antenna of each base station.

For example, if there is a difference of several tens of dB between the received voltage from the reference station and the received voltage at your own station, the one with the higher reception level will not be able to receive it accurately due to sensitivity suppression etc. was there.

For example, conventional AGC receivers suffer from insufficient dynamic range for gain adjustment and response time.

An object of the present invention is to provide a phase synchronization receiver that solves these problems.

(Means for Solving the Problems) A feature of the present invention is that in a mobile communication system that uses a plurality of small wireless zones to cover a wide area, a signal is transmitted between a plurality of wireless base stations installed in each small wireless zone. In order to achieve phase synchronization, in a receiver installed at another wireless base station for receiving the radio waves of the wireless base station that serves as the reference phase of the signal, the receiver has a decoding circuit for decoding the received signal. , a phase synchronization reception having a variable attenuator that attenuates received radio waves, and in which the attenuation amount of the variable attenuator is switched immediately after the decoding circuit detects a predetermined special signal or after a predetermined period of time has elapsed from the detection. It's on the machine.

(Function) According to the present invention, a variable attenuator is inserted into the reception input of the phase synchronization receiver to reduce the reception voltage to a standard reception voltage when the reception voltage is high.

The amount of attenuation of the variable attenuator is switched according to the decoded signal from the decoding circuit so that it is large when the received voltage is high and becomes small (or O) when the received voltage is low. Therefore, a phase synchronization receiver with a wide dynamic range can be obtained.

(Example) FIG. 1 is a diagram for explaining the present invention in detail. Hereinafter, the present invention will be explained in detail based on the drawings.

In FIG. 1, a receiver 10 includes a variable attenuator 10a for attenuating received radio waves and a receiver 10b. A phase comparator 12 includes a decoding circuit 12a for decoding a received signal and a phase comparator circuit 12b, and phase difference information is obtained from the output of the phase comparator circuit 12b. The attenuation amount of the variable attenuator 10a is determined by the decoding circuit 1
After a predetermined time after 2a receives special signal A (Fig. 4), the attenuation amount is controlled so that it becomes small (in order to receive the weak radio waves from the reference station), and when special signal B is received, the attenuation amount becomes large. Ru.

The transmission output of the reference station is IOW, and the gain of the transmitting and receiving antenna is 5.
dBi, distance between reference station and surrounding stations is 10000 m
If the coupling attenuation between the transmitting and receiving antennas at the peripheral station is 40 dB within line of sight, the wavelength of the radio wave used is 0.3 m, and the input impedance of the receiver is 50 Ω, then the radio waves from the reference station at the output terminal of the receiving antenna of the peripheral station are The received voltage is = 101og101o +5-25-201o*x
*1000010.3) +5+ 101101o 5
0) +120 = 50.5 (dBuV) Received voltage due to radio waves from the peripheral station at the output terminal of the receiving antenna of the peripheral station = 101og (10101o + 101101o umbrella 50
)+120=113.0 (dBuV), which means that it is necessary to receive a signal with a level difference of 60 dB or more between the signal from the reference station and the signal from the peripheral station. A generally known method for realizing a receiver with such a wide dynamic range is the AGC method, in which the gain of the amplifier in the receiver is made variable and its output is made constant depending on the received input. has the problems mentioned above.

In the case of phase synchronization according to the present invention, as shown in FIG. 4(C), after receiving the special signal A included in the radio waves from the local station, the radio waves of the local station will be released after a certain time α seconds. Since the station stops and receives weak radio waves from the reference station, an attenuator 10a is added to the phase synchronization receiver to reduce the reception voltage to the standard reception voltage, as shown in Fig. 1. By removing the attenuator 0 seconds after detecting the special signal A included in the received signal and inserting the attenuator after receiving the special signal B, the appropriate Obtaining reception input can be easily realized.

In other words, in Fig. 1, when receiving the radio waves from the local station, the attenuator operates to the extent that the received voltage becomes the standard received voltage, but the receiver's decoding circuit When α seconds have elapsed after detecting the special signal A, the attenuation amount of the attenuator is reduced at the timing of stopping the transmission of radio waves from the surrounding station, so that the voltage level of the radio waves from the reference station is received at the standard voltage. It is meant to be.

Such a variable attenuator can be easily realized by changing the bias voltage of the PIN diode, and a decoder for detecting the special signal A and special signal B for phase synchronization is necessary for measuring the phase difference and has been conventionally used. Since the present invention does not require any special provision, it can be realized economically.

(Effects of the Invention) As explained above, the present invention provides phase synchronization reception with a wide dynamic range by controlling the amount of attenuation of the attenuator provided in the receiver using the control signal from the originally required decoder. machine can be realized economically. Therefore, regardless of the difference in the strength of the received radio waves, only one system of antenna system and receiver is sufficient.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a phase synchronization receiver according to the present invention, FIGS. 2 and 3 are diagrams for explaining phase synchronization, and FIG. 4 is a diagram for explaining conventional phase synchronization. 10; receiver, 10a; variable attenuator, 10
b; receiving section; 12a; decoding circuit; 12; phase comparator; 12b; phase comparison circuit.

Claims (1)

[Claims] In a mobile communication system that uses a plurality of small wireless zones to cover a wide area, the signal In a receiver installed at another wireless base station for receiving radio waves of a wireless base station that serves as a phase reference, the receiver includes a decoding circuit for decoding the received signal, and a variable attenuator for attenuating the received radio waves. A phase synchronization receiver, characterized in that the attenuation amount of the variable attenuator is switched immediately after detection of a predetermined special signal by the decoding circuit or after a predetermined period of time has elapsed since the detection.