JPS638657B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diversity communication method used to overcome the fading phenomenon and increase line reliability when transmitting information using a wireless communication method with a relatively long relay distance. The present invention also relates to a diversity communication system that is highly economical in terms of line configuration and frequency usage using wireless communication devices.

The diversity communication method is a very effective method for increasing the line reliability of wireless communication methods, but on the other hand, it is not economical because it requires the use of antennas, radio equipment, and frequencies corresponding to the order of diversity. It's a burden. Therefore, it is desirable to increase the order of diversity or achieve the effect using less hardware and frequency.

Conventional diversity communication systems basically used space diversity and frequency diversity, and additionally combined angular diversity, polarization diversity, and time diversity to form higher-order diversity. . However, spatial diversity requires the use of four-sided antennas (or three-sided antennas if economic efficiency is important), and frequency diversity uses at least two radio frequencies, resulting in poor frequency utilization. In addition, angular diversity and polarization diversity are rarely used alone due to their effectiveness, and furthermore,
Although time diversity is excellent in principle,
Because it requires the use of advanced signal processing technology and its application is limited to digital communications, it is often used in combination with space diversity and frequency diversity.

Based on the above considerations, the present invention aims to provide a diversity communication system that is economically superior and has a high diversity effect.

According to the present invention, the transmitting side transmits the same information as a polarization diversity signal with a delay time difference, and the receiving side receiving the signal receives the information with a delay time difference opposite to that of the transmitting side. A diversity communication system is obtained in which diversity combining is performed after adjusting the times to be the same.

Therefore, the present invention does not use a large number of antennas as in space diversity, nor does it use multiple radio frequencies as in frequency diversity, but instead uses time diversity as its main component and combines polarization diversity to achieve analog communication. is also a diversity communication method that can also be applied to digital communication. Furthermore, since the diversity communication system according to the present invention essentially does not include a delay time difference caused by a propagation path difference caused by angular diversity, a circuit for compensating for this is not required.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the diversity communication system according to the present invention. 1st
In the figure, 1 is a baseband signal input of information to be transmitted, 2 is a modulation circuit, 3 is a delay circuit (delay time = τ), and 4 and 5 are transmitters (frequency conversion circuit, transmitting station generator, power amplifier, etc.). ), 6 and 7
is a branching circuit, 8 and 9 are receivers (including a three-band waver, a frequency conversion circuit, a receiving station generator, an intermediate frequency amplifier, etc.), 10 is a delay circuit (delay time = τ), and 11 is a diversity signal synthesis circuit. , 12 is a demodulation circuit, 13
is the baseband signal output of the received information, 14 is the antenna, and V and H are the vertical and horizontal polarization feeds of the shared polarization feed, respectively. Further, 101 to 114 represent hardware of the opposing station, and have the same functions as the corresponding 1 to 14.

Figure 1 shows an example where the information is bidirectional like a telephone signal, and when the information is unidirectional like a TV signal or data signal, the transmitting station only uses the transmitting system and the receiving station. The station only needs a receiving system, and a branching circuit is not required.

If we explain the case where the diversity signals radiated from the 14 antennas are received by the 114 antennas in FIG. 1, it is obvious that the same applies to the case in the opposite direction. i.e. 1
information is sent out from 14 V polarization feeds through circuits 2, 4, and 6, and
It is also transmitted from 14 H polarization feeds with a delay time τ through the circuit, and is received by 114 V polarization feeds and H polarization feeds, respectively. At this time, the same information is received in the V polarization feed of 114 and the H polarization feed with a time difference of delay time τ, so in the case of flat fading shown in _FIG . Even if the V polarization feed is received below the reception limit, it is received normally at the H polarization feed of 114 at time t = t ₁ + τ, so the line will not be disconnected, and the frequency shown in Figure 2b Also in the case of selective fading, at time t= _t2 , 11
Even if it is received below the reception limit in the V polarization feed of 4, it is normally received in the H polarization feed of 114 at time t=t ₁ +τ, so it is expected that the line will not be disconnected. Here, ₀ in FIGS. 2a and 2b represents the frequency of the radio carrier wave. Also, the delay time τ
The selection of
It may be estimated from the propagation path characteristics etc. to obtain the desired diversity effect.

Next, the V polarization feed and H
The signals received in the polarization feed are each 10
The signal passed through the receiver 8,109 and further received by the V polarization feed is delayed by a delay time τ by 110, adjusted at the same time as the signal received by the H polarization feed, and diversity-combined by 111.
12, and a baseband signal output 113
becomes.

From the above, it is clear that the present invention is more economical than the conventional diversity communication system based on space diversity and frequency diversity, and can obtain the same diversity effect. That is, the fact that the number of antennas and frequencies used is small is a great advantage in constructing an economical wireless communication line. In addition, time diversity can be applied to both analog communication and digital communication, and the setting of delay time τ can be easily changed even after the line is constructed, providing flexibility in obtaining sufficient diversity effects. It has advantages not found in other methods.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the diversity communication system according to the present invention, and FIG. 2 is a conceptual diagram of fading for explaining the diversity effect of the present invention. , b show the case of frequency selective fading. Explanation of symbols: 1... Baseband signal of information to be transmitted, 2... Modulation circuit, 3... Delay circuit, 4, 5... Transmitter, 6, 7... Branching circuit, 8, 9... Receiver, 10
...Delay circuit, 11...Diversity signal synthesis circuit,
12... Demodulation circuit, 13... Baseband signal output of received information, 14... Antenna, 101~
Reference numeral 114 represents opposing stations having the same functions as those of 1 to 14, respectively.

Claims (1)

[Claims] 1 The transmitting side transmits the same information as a polarization diversity signal with a delay time difference, and the receiving side that receives the signal adjusts the arrival time of the information to be the same with a delay time difference opposite to that of the transmitting side. After that,
A diversity communication method characterized by diversity combining.