JP2011055078A - Time division multiplexing wireless system and reflected signal attenuation method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflected signal attenuation method of a time division multiplexing wireless system, which protects a receiving amplifier in a transmission section without degrading a receiving noise index. <P>SOLUTION: The time division multiplexing wireless system has a first directional coupler 22 which branches transmission signals from a transmission amplifier 21, an amplitude phase adjustment circuit 1 which adjusts the amplitude and phase of the transmission signals branched by the first directional coupler, and a second directional coupler 2 which synthesizes output signals from the amplitude phase adjustment circuit with reflected power from an antenna. In a transmission section, reflected power attenuation signals which have the same amplitude and reverse phase to that of reflected power from the antenna are generated by the amplitude phase adjustment circuit 1, and the attenuation signals are reverse-phase synthesized with the reflected power from the antenna by the second directional coupler 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a time division multiplexing (TDD) wireless communication system and a reflected signal attenuation method thereof.

  FIG. 3 is a circuit diagram showing a configuration of a high-frequency unit of a conventional general time division multiplexing TDD (Time Division Duplexing) type radio communication system. The radio communication system shown in FIG. 3 includes a transmission unit having a transmission circulator 24 at the output of the transmission amplifier 21, a reception unit having a reception amplifier 25 at the output of the reception circulator 32, and a transmission / reception switching for switching between the transmission unit and the reception unit. The switch 31 is configured.

  The TDD wireless communication system is a communication method in which the transmission section and the reception section are alternately switched for each frame on the time axis using the same transmission / reception frequency band, so that only the transmission section operates in the transmission section, and the reception section is Only the receiving unit needs to operate. Therefore, in the transmission section, power is supplied to the transmission amplifier 21 to operate the transmission amplifier 21, and the power supply to the reception amplifier 25 is interrupted to stop the operation of the reception amplifier 25.

  On the other hand, in the reception period, the power supply to the transmission amplifier 21 is interrupted, the operation of the transmission amplifier 21 is stopped, the power is supplied to the reception amplifier 25, and the reception amplifier 25 is operated. The transmission / reception change-over switch 31 is connected to the transmission circulator 24 side in the transmission section in which the transmission amplifier 21 operates and outputs a transmission signal, and receives the reception amplifier by reflected power input to the reception amplifier 25 by reflection from the antenna terminal 12. This ensures isolation of the receiving section in the transmission section so that 25 is not damaged. In the reception section, the transmission / reception changeover switch 31 is connected to the reception circulator 32 side.

  In the system of FIG. 3, since the transmission / reception changeover switch 31 is mounted on both the transmission system and the reception system, the passage loss of the transmission / reception changeover switch 31 affects both transmission characteristics and reception characteristics. That is, an increase in power consumption occurs due to an increase in the output power of the transmission amplifier 21 to compensate for the passage loss of the transmission / reception changeover switch 31, or an increase in noise figure corresponding to the passage loss of the transmission / reception changeover switch 31 occurs. In FIG. 3, 11 is a transmission input terminal (transmitter side terminal) of the high frequency section, 13 is a reception output terminal (receiver side terminal) of the high frequency section, and 33 and 34 are terminators for the circulator.

  On the other hand, FIG. 4 shows an example in which the mounting position of the receiving unit and the transmission / reception change-over switch 31 is changed with respect to the configuration of FIG. In the system of FIG. 4, a transmission / reception changeover switch 31 is arranged between the transmission circulator 24 and the circulator terminator 34, and the transmission / reception changeover switch 31 is arranged in the reception unit. In this system configuration, the transmission signal does not pass through the transmission / reception changeover switch 31, and therefore the transmission characteristics are not affected.

  On the other hand, the received signal is routed by one extra circulator compared to the configuration of FIG. 3, so that the passage loss is increased, that is, the noise figure is increased as compared with FIG. Therefore, the system of FIG. 4 can be said to have a configuration in which priority is given to lower power consumption of the transmission system than in FIG. 3, and the noise figure of the reception system is sacrificed. The use of the transmission / reception change-over switch 31 in any of the configurations of FIGS. 3 and 4 is accompanied by deterioration of the reception noise figure corresponding to the passage loss of the transmission / reception change-over switch 31. The TDD radio communication system is described in, for example, Patent Documents 1 and 2.

JP 2008-306370 A Japanese Patent Laid-Open No. 08-279705 JP 09-116459 A

  As described above, in the configuration using the transmission / reception change-over switch in the conventional wireless communication system, the reception noise figure deteriorates corresponding to the passage loss of the transmission / reception change-over switch. Patent Document 3 adjusts the level and phase of a transmission signal component that leaks from the transmitter connection circulator to the receiver side, and adjusts the level and phase of the transmission signal component input to the receiver side directional coupler. Although it is described that the interference caused by the transmission signal is eliminated, the purpose is to eliminate the interference of the transmission signal, and the deterioration of the reception noise figure corresponding to the passage loss when the transmission / reception changeover switch is used is improved. It is not a thing.

  An object of the present invention is to provide a time division multiplex radio system and a reflected signal attenuation method thereof capable of protecting a reception amplifier in a transmission section without causing deterioration of a reception noise figure.

  In the present invention, instead of using a transmission / reception switch such as a high-frequency switch for the main signal system, the transmission signal of the transmission amplifier is branched into a transmission section in which the transmission amplifier operates and outputs the transmission signal. It has an amplitude phase adjustment circuit for adjusting the amplitude and phase of the transmission signal. Then, the reflected power is attenuated by synthesizing the output signal of the amplitude phase adjustment circuit with the reflected power from the antenna in reverse phase.

  According to the present invention, the reflected power input to the receiving amplifier can be attenuated in the opposite phase due to reflection from the antenna terminal without using the transmission / reception switch for the main signal system, and reception due to the transmission loss of the transmission / reception switch. The deterioration of noise characteristics can be prevented.

It is a block diagram which shows one Embodiment of the reflected signal attenuation circuit which concerns on this invention. It is a block diagram which shows an example of an amplitude phase adjustment means. It is a block diagram which shows the high frequency part structure of the radio | wireless communications system of the conventional general time division multiplex (TDD) system. It is a block diagram which shows another high frequency part structure.

  Next, embodiments for carrying out the invention will be described in detail with reference to the drawings. First, an outline of the present invention will be described. The present invention uses a transmission / reception switch (transmission / reception switch 31 in FIGS. 3 and 4) such as a high-frequency switch in the main signal system in a high-frequency unit of a time division multiplexing (TDD) wireless communication system such as WiMAX. The reception amplifier is protected by attenuating the reflected power from the antenna terminal of the transmission signal by the amplitude phase control means provided in a path different from the main signal system.

  That is, the output power of the transmission amplifier is branched in addition to the two paths of the path for transmitting the output power of the transmission amplifier from the antenna terminal to the antenna and the path for transmitting the output power from the antenna to the reception amplifier via the antenna terminal. A path for transmitting the transmission signal to the reception amplifier via the amplitude phase adjusting means is newly provided.

  Then, in the transmission section, that is, in the transmission section in which the transmission amplifier operates and outputs a transmission signal, the reflected power input to the reception amplifier by reflection from the antenna terminal is converted to the power of the path provided with the amplitude phase adjusting means. To attenuate by reverse phase synthesis. For this reason, it is possible to attenuate the reception amplifier to below the maximum input rated power without damage or the like without using a transmission / reception switch.

  The present invention eliminates the need for a transmission / reception switch mounted in the main signal system, which is a factor that deteriorates the noise figure (Noise Figure, NF), which is the main index of the high-frequency characteristics of the reception system, as described above. In the TDD wireless communication system, it is possible to improve the high frequency characteristics of the high frequency section.

  FIG. 1 is a block diagram showing an embodiment of a time division multiplex radio system according to the present invention. 1, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 1, a transmission signal from a transmitter (not shown) is input from a transmission input terminal 11 of a high frequency unit and amplified by a transmission amplifier 21.

  The signal power amplified and output by the transmission amplifier 21 is output to the antenna terminal 12 through the directional coupler 22 and the transmission circulator 24, and is radiated from an antenna (not shown). The main signal system power is partially reflected by the antenna terminal 12 in accordance with the reflection loss, and is input to the directional coupler 2 through the transmission circulator 24.

  Similarly, the signal power amplified and output by the transmission amplifier 21 is input to the amplitude phase adjusting unit 1 via the coupling terminal side of the directional coupler 22, and is input to the directional coupler 2 via the amplitude phase adjusting unit 1. Entered. The amplitude phase adjusting unit 1 adjusts the amplitude and phase of the transmission signal branched from the directional coupler 22.

  Here, the amplitude phase adjusting means 1 controls the amplitude amount and the phase amount to have the same amplitude and opposite phase as the reflected power from the antenna terminal 12. Therefore, in the transmission section in which the transmission amplifier 21 operates and outputs a transmission signal, the output power of the directional coupler 2, that is, the input power input to the reception amplifier 25 via the reception circulator 32 is received. The amplifier 25 is attenuated to a power intensity that is not damaged.

  FIG. 2 is a block diagram showing an example of the amplitude / phase adjusting means 1. In the figure, 41 is a variable phase shifter, 42 is a variable attenuator, 43 is an amplifier, and 44 is a control unit for controlling the phase amount of the variable phase shifter 41 and the attenuation amount of the variable attenuator 42. The amplitude phase adjusting unit 1 attenuates the reflected power input to the receiving amplifier by reflection from the antenna terminal 12 by controlling the phase amount and attenuation amount of the transmission signal branched from the directional coupler 22 as described above. Let The arrangement of the variable phase shifter 41 and the variable attenuator 42 may be switched.

  On the other hand, in the reception section, the reception signal from the antenna terminal 12 is input to the reception circulator 32 via the directional coupler 2, and is input from the reception circulator 32 to the reception amplifier 25. The reception signal is amplified by the reception amplifier 25 and input to the receiver from the reception input terminal 13 of the high frequency unit.

  As a specific example, the output power of the transmission amplifier 21 is 10 W (+40 dBm), the reflection loss of the antenna terminal 12 is 15 dB, and the maximum rating at which the reception amplifier 25 is not damaged is +10 dBm. The passing losses of the directional couplers 22 and 2, the transmission circulator 24, and the reception circulator 32 are ignored for simplicity.

  Under this condition, when there is no path of the amplitude phase control means 1, the power output from the transmission amplifier 21 is reflected by the antenna terminal 12, and the reflected power intensity input to the reception amplifier 25 is (+40 dBm) − ( 15 dB) = + 25 dBm, which is 15 dB higher than the maximum rating +10 dBm of the receiving amplifier 25.

  Assuming that the passing loss of the directional couplers 22 and 2 with respect to the main signal system is suppressed to a value smaller than 0.3 dB of the passing loss of a general transmission / reception selector switch, the coupling amount of the directional couplers 22 and 2 is 15 dB. To do. In order for the amplitude / phase control means 1 to combine the reflected power from the main signal system antenna terminal 12 with the directional coupler 2 by the directional coupler 2, the amplitude / phase control means 1 has a performance of 15 dB gain and output power +40 dBm. is required.

  In order to ensure the linearity of the radio characteristics, the transmission amplifier 21 of the main signal system is operated with a back-off of 10 dBc, for example, when the transmission output is 40 dBm, and the saturation output of the transmission amplifier 21 is (+40 dBm) + ( It is common to have a capacity of 10 dB) = + 50 dBm = 100 W. However, the capability equivalent to the amplifier necessary for the amplitude / phase control means 1 is not required if the output signal has high linearity and can simply output the output power +40 dBm.

  Therefore, while the main signal transmission amplifier 21 has a saturation output of 100 W, an output of 10 W is sufficient for the saturation output of the amplitude phase control means 11. By controlling the amplitude phase of the amplitude phase control means 1, a signal having the same amplitude and opposite phase as the reflected power from the antenna terminal 12 can be generated, and attenuation of 15 dB can be realized by power combining by the directional coupler 2, Damage to the receiving amplifier 25 in the transmission period can be avoided.

  Attenuation of 15 dB by power combining can be achieved by suppressing the phase error to about 10 ° if the amplitude error of both systems is 0 dB, and to an amplitude error of about 1.5 dB if the phase error is 0 °. .

DESCRIPTION OF SYMBOLS 1 Amplitude phase adjustment means 2, 22 Directional coupler 3, 23 Terminator for directional coupler 11 Transmitter side terminal 12 Antenna terminal 13 Receiver side terminal 21 Transmission amplifier 24 Transmission circulator 25 Reception amplifier 31 Transmission / reception changeover switch 32 Reception Circulator 33, 34 Circulator Terminator 41 Variable Phase Shifter 42 Variable Attenuator 43 Amplifier 44 Control Unit

Claims (6)

A transmission unit having a transmission amplifier for amplifying a transmission signal, and a reception unit having a reception amplifier for amplifying a reception signal;
In a time division multiplex radio communication system for switching the operation of the transmitter and the receiver in a transmission section in which a transmission signal of the transmission amplifier is transmitted from an antenna and a reception section in which a reception signal from the antenna is received by the reception amplifier. There,
An amplitude phase adjustment circuit for branching a transmission signal from the transmission amplifier and adjusting an amplitude and a phase of the branched transmission signal, and an output signal of the amplitude phase adjustment circuit is combined with a reflected power from the antenna in a reverse phase A time division multiplex radio system characterized in that the reflected power is attenuated. A transmission unit having a transmission amplifier for amplifying a transmission signal, and a transmission circulator for guiding the transmission signal from the transmission amplifier to an antenna;
A reception unit that amplifies a reception signal from the antenna and a reception circulator that guides the reception signal to the reception amplifier;
A time division multiplex radio communication system that switches the operation of the transmission unit and the reception unit between a transmission period in which a transmission signal of the transmission amplifier is output from the antenna and a reception period in which a reception signal from the antenna is received by the reception amplifier. Because
An amplitude phase adjustment circuit for branching a transmission signal from the transmission amplifier and adjusting an amplitude and a phase of the branched transmission signal;
Combining means for combining the output signal from the amplitude and phase adjustment circuit with the reflected power from the antenna;
The time division multiplex radio system characterized in that the reflected power is attenuated in the transmission section by combining the output signal from the amplitude phase adjustment circuit with the reflected power from the antenna by the synthesizing unit. A transmission unit having a transmission amplifier for amplifying a transmission signal, and a transmission circulator for guiding the transmission signal from the transmission amplifier to the antenna;
A reception unit that amplifies a reception signal from the antenna and a reception circulator that guides the reception signal to the reception amplifier;
Time division for switching the operation of the transmission unit and the reception unit between a transmission period in which a transmission signal of the transmission amplifier is output from the antenna and a reception period in which a reception signal from the antenna is received by the reception amplifier. A multiple radio communication system,
A first directional coupler for branching a transmission signal from the transmission amplifier;
An amplitude phase adjustment circuit for adjusting the amplitude and phase of the transmission signal branched by the first directional coupler;
A second directional coupler that combines the output signal from the amplitude and phase adjustment circuit with the reflected power from the antenna;
In the transmission section, the amplitude phase adjustment circuit generates a reflected power attenuation signal having the same amplitude and opposite phase as the reflected power from the antenna, and the attenuation signal is output from the antenna by the second directional coupler. A time division multiplex radio system characterized in that the reflected power is attenuated by performing reverse phase synthesis with the reflected power. A transmission unit having a transmission amplifier for amplifying a transmission signal, and a reception unit having a reception amplifier for amplifying a reception signal;
The time division multiplex radio communication system for switching the operation of the transmission unit and the reception unit between a transmission period in which a transmission signal of the transmission amplifier is transmitted from an antenna and a reception period in which a reception signal from the antenna is received by the reception amplifier. A reflected signal attenuation method,
The amplitude and phase of a transmission signal branched from the transmission amplifier by an amplitude phase adjustment circuit in the transmission section are adjusted, and the output signal of the amplitude and phase adjustment circuit is combined with the reflected power from the antenna to produce the reflected signal. A method for attenuating a reflected signal in a time division multiplex radio system, wherein the power is attenuated. A transmission unit having a transmission amplifier for amplifying a transmission signal, and a transmission circulator for guiding the transmission signal from the transmission amplifier to an antenna;
A reception unit that amplifies a reception signal from the antenna and a reception circulator that guides the reception signal to the reception amplifier;
A time division multiplex radio communication system that switches the operation of the transmission unit and the reception unit between a transmission period in which a transmission signal of the transmission amplifier is output from the antenna and a reception period in which a reception signal from the antenna is received by the reception amplifier. The reflected signal attenuation method of
Adjust the amplitude and phase of the transmission signal branched from the transmission amplifier by the amplitude phase adjustment circuit in the transmission section,
A reflected signal attenuation method for a time division multiplex radio system, wherein the reflected power is attenuated by combining the output signal from the amplitude phase adjustment circuit with the reflected power from the antenna in reverse phase by a combining means. A transmission unit having a transmission amplifier for amplifying a transmission signal, and a transmission circulator for guiding the transmission signal from the transmission amplifier to the antenna;
A reception unit that amplifies a reception signal from the antenna and a reception circulator that guides the reception signal to the reception amplifier;
Time division for switching the operation of the transmission unit and the reception unit between a transmission period in which a transmission signal of the transmission amplifier is output from the antenna and a reception period in which a reception signal from the antenna is received by the reception amplifier. A method for attenuating reflected signals in a multiple wireless communication system, comprising:
A transmission signal from the transmission amplifier is branched by a first directional coupler in the transmission section;
Adjusting the amplitude and phase of the transmission signal branched by the first directional coupler by the amplitude phase adjustment circuit;
The reflected signal of the time division multiplex radio system, wherein the reflected power is attenuated by anti-phase combining the output signal from the amplitude phase adjustment circuit with the reflected power from the antenna by a second directional coupler. Attenuation method.