JPS5899038A - Optical and milimeter wave complementary communication system - Google Patents

Abstract

PURPOSE:To imporve the reliability of lines and to extend the repeating section, by using the constitution of the communication system in which disadvantages of an optical wave and a millimeter wave on the propagation characteristics are complemented with each other. CONSTITUTION:Millimeter wave communication devices 2, 6 having a frequency band in which attenuation due to rainfall is larger than that in optical waves, are provided in addition to optical wave communication devices 1, 5, and the attenuation due to rain is covered with the optical systems 1, 5 and the attenuation due to mist and snow is compensated by the devices 2, 6. Based on information representing the state of line from a reception signal or meteorological information obtained from a weather sensor 8, signals of the optical or millimeter wave communication devices are selected, and the output signal is applied to an output terminal 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a communication method that uses a millimeter-wave wireless method in combination with a millimeter-wave wireless method, or a millimeter-wave wireless A communication method that uses a light wave communication method in combination to back up line failures during heavy rain, or a communication method that uses light waves and a millimeter rain communication method to operate in a complementary manner, improving the reliability of communication lines. and a new communication method that makes it possible to extend the relay section.

Conventionally, space propagation communication systems using light waves have been considered, but high attenuation occurs due to scattering phenomena caused by fog and smog with particle sizes similar to the wavelength existing in the air, making it difficult to achieve high line reliability and long relay intervals. It is said that it cannot be expected. For example, the attenuation σ of a light wave per 1 km at a visibility V (km) is )' (aB/kn)=15/V. Therefore, when visibility is 170 m, 1 k
Approximately 100 dB of attenuation will occur per m. Tokyo,
In cities such as Yokohama 2 and Nagoya, visibility is said to be 150 to 200 meters for about 0.1 inch (9 hours) a year, making it difficult to achieve high line reliability of around 0.1% using light waves, and long Line setup is possible and is actually happening. (Takashi Igarashi, “On the current status of laser wave propagation and its use”,
IEICE Journal Vot59-A 1) On the other hand, 30G
Millimeter wave radio waves exceeding Hz are highly scattered by raindrops during heavy rainfall, so from the standpoint of rain attenuation, it is difficult to establish highly reliable and long relay sections.

The present invention is based on the fact that light waves are significantly attenuated by fog and smog, which has been known in the past, but millimeter waves do not attenuate to the extent that is considered a problem. By clarifying the area that increases due to waves, we can improve line reliability, expand the relay area, and simplify the characteristics of equipment by installing optical wave and millimeter rain communication systems together and compensating for each other's shortcomings. This invention relates to a communication method characterized by the ability to measure.

The attenuation of light waves due to fog sometimes reaches 100 dB/km, but for millimeter wave radio waves, the attenuation is 0 at 40 to 50 GHz.
, 1 dB/km s 1 dB at 100 GHz
It is known that the amount is extremely low, at just under /ka.

Next, we will consider propagation during rainfall. Although this point has not been clearly demonstrated in the past, we present theoretical values for the attenuation of millimeter waves due to rain in the range of 30 to 150 GHz, and also provide actual measured values of rain attenuation of laser waves obtained at Bell Laboratories. (T, S, Chu and D-C-Hogg
+ 'Effects of Precipitati
on onPropagation at O,63,
3,5, and 10.6 Microns”.

THE BELL SYSTEM TECHNICAL
JOURNAL, MAY-JtJNE1968) and the attenuation with a 6 dB margin added to the actual measured value.
As shown in the figure. In FIG. 1, the solid line represents millimeter waves, the broken line represents visible light, and the dashed-dotted line represents actual measured values of visible light including 6 dB marnon. In addition, 3.5 μm.

A similar tendency is shown for light waves in the infrared region of 10.5 μm. These advantages of light waves are particularly noticeable in the heavy rainfall region of 50 to 150 + am/H, which is a problem in millimeter wave communications, and the effect is even more remarkable in higher frequency bands such as 50 to 150 GHz. I understand. The reason why the loss of visible laser waves is lower than that of millimeter waves is that the raindrop particle size is close to the wavelength of millimeter waves, so the scattering effect of millimeter waves is large, and the attenuation increases significantly, whereas optical waves For example, the raindrop size is 1,000 wavelengths.
This is due to the fact that the water is 0 times larger, and as the water is a transparent sphere, there is no absorption loss, so the amount of energy transmitted increases, and the number of raindrops is smaller than that of fog, for example, about 1/1 millionth of a unit volume. It can be explained.

Therefore, the optical wave system can be provided with a rain attenuation margin. Figure 2 shows the transmission distance and allowable rainfall intensity R (rm/
H) shows the relationship. In Figure 2, A(5) has an allowable margin of 20 dB, B has an allowable margin of 40 dB,
C shows the case of 60 dB.

For example, if the 0.1% rainfall intensity is 85w/H,
The allowable transmission distance can be changed as shown in Figure 3.

It can be seen that the above results are greater than the allowable transmission distance (100 dB/km 2 ) determined from the attenuation of light waves due to fog. In other words, since the millimeter wave system is attenuated by fog, the transmission distance can be significantly increased.

On the other hand, the permissible attenuation amount for fog required for millimeter wave systems is
As mentioned above, 0.1 dv at 40-50 GHz
Even at m -100 GHz, the attenuation margin is extremely small at less than 1 dB/km, so if the transmission distance is determined as shown in FIG. 3, it can be seen that an overall attenuation margin of about 4 dB is sufficient.

Note that in areas with snowfall, it is thought that light waves have greater attenuation than millimeter waves.

Therefore, let's consider that millimeter waves also bear the burden of attenuation due to snowfall. For millimeter waves, attenuation due to snow is more of a problem than fog. In particular, wet snow (6) has a high moisture content, and the loss at millimeter waves is large.

On the other hand, light waves are expected to experience large losses due to fine, dry snow.

Normally, the intensity of snowfall is 1 ttan / 1 in terms of water.
It is said that 0 public tax is the most common, but due to this, 50G
5-6 dB/kms at frequencies around Hz 80-12
At 0 GHz, an attenuation margin of approximately 10 dB/km should be considered. (Nishitsugu, Hirayama “Abnormal attenuation of radio waves due to snowfall”, IEICE Journal Vot, 54-B,
10) Therefore, in areas with a lot of snow, 1
An attenuation margin of 0 dB/+n shall be considered.

On the other hand, in the case of a millimeter wave system alone, at 100 GHz, the required rain attenuation is 3QdB/T (R = 85mm/T).
km, so in the case of light wave and millimeter wave complementary communication systems,
This means that the allowable attenuation margin required for millimeter wave systems can be a very small value. In addition, the required attenuation amount required for the light wave system is 16 dB/k for a rainfall of 85 dB/h.
Considering the design margin of m t 6 dB, it is 22 dB/k.
m), the required attenuation is smaller than that required for millimeter waves alone, and the effect of the complementary communication system using light waves, which is required in the case of light waves alone, is obvious. In this way, a communication system that improves line reliability by backing up line failures caused by fog or snow in light wave communication equipment with simple millimeter wave or other wireless equipment that has an attenuation margin that is a fraction of that of light wave systems. can be realized.

FIG. 4 shows an example of the configuration of this communication system. Reference numeral 1 indicates a transmitter of a light wave communication device, and reference numeral 2 indicates a transmitter of a millimeter wave communication device. Information to be transmitted is applied from the terminal 3, and is applied to either the transmitter 1 or 2 by selecting the transmitter switch 4. 5
6 indicates the receiving section of the light wave communication device, and 6 indicates information indicating the receiving section of the millimeter wave communication device, such as information indicating the state of the line such as received signal level, noise level, or error rate, visibility meter, and rainfall intensity. This circuit selects a signal for a light wave or millimeter wave communication device based on weather information obtained from a weather sensor 8 such as a meter. The receiver selection circuit 7 makes a selection using the receiver switch 9 and supplies an output signal to the output terminal 10 .

The transmitters 1 and 2 are also provided with a transmitter selection circuit 1 for selecting light waves and millimeter waves, so that unnecessary operations of the transmitter 1 or 2 can be stopped. This control signal is indicated by 12. In particular, when not using a millimeter wave system that tends to cause interference with other lines, controlling the transmission so as not to transmit has the effect of leading to effective use of the frequency band. Assuming bidirectional communication, the information that determines the operation of the transmitting section selection circuit 11 is the line from the receiving section (not shown in FIG. 3) attached to the transmitting sections 1 and 2. Condition hail signal 14
This can be done by using information from the weather sensor 13, or by using information from the weather sensor 13. Regarding the control status of both stations, information is mutually exchanged through a normally established control line between the two stations to improve the operation, which is the same as in a normal communication system.

As explained above, by creating a communication system configuration that mutually compensates for the weaknesses in the propagation characteristics of light waves and millimeter waves) (9) (1) Compared to the case of each separately, the line reliability is
There is a possibility that it can be improved by more than one order of magnitude.

(11) For the same line reliability, the transmission distance may be doubled or more.

(i;) Since the amount of attenuation required for both light wave and millimeter wave communication devices is reduced, the device can be made more economical. In particular, the amount of attenuation required for millimeter wave systems is extremely small, making it possible to save money and reduce losses due to parallel installation.

(iv) It becomes possible to open the way for the use of millimeter wave radio waves such as 50 to 150 GHz, whose practicality has been questioned in the past due to rain attenuation, in communication systems.

(V) A backup device is usually required in communication systems1
However, both light wave and millimeter wave types can also be used for relief in the event of equipment failure.

(vi) Since the rate of fog and heavy rainfall is generally considered to be less than a few inches per year, (a) Should we adopt a method in which light waves are used primarily and millimeter waves are used as backup during foggy conditions? (b) Millimeter waves (10) Either operate as a gold main and switch to light waves when it rains, or (c
) There are three possible operation methods: operate both systems at the same time and select the best line. The selection of this b-shift operation method can be made depending on weather conditions and the usage status of millimeter wave radio waves.

(vii) In the operation method of (vi) (a) above,
It can be separated from other lines by rain attenuation, making it possible to set up multiple routes and reuse the same frequency.

(Vlil) Since the required attenuation of the millimeter-IJ wave system can be reduced, the transmission output can be reduced, interference in mutual lines can be reduced, and the millimeter wave band, which has large circuit loss, can be used.

According to the present invention, the shortcomings of millimeter waves and light wave spatial propagation systems are mutually interpolated, so line reliability and relay section distance are improved. It can be used for many purposes such as inter-office communication.

[Brief explanation of drawings]

Figure 1 shows a comparison of the attenuation characteristics during propagation in rain for mi') waves and light waves. Figure 2 shows the transmission distance versus allowable rainfall intensity using the allowable attenuation of the light wave communication system as a parameter. FIG. 3 is a diagram showing the transmission distance of light waves determined from rain attenuation. FIG. 4 is a diagram showing the configuration of a communication system according to an embodiment of the present invention. ! , 2... Transmission unit, 4, 9... Switch, 5, 6...
... Receiving section, 7, 11... Selection circuit 1.8, 1.9.
...Weather sensor.

Claims (1)

[Scope of Claims] (Li) A millimeter wave communication device in a frequency band where rainfall attenuation is greater than light waves is attached to the light wave communication device, and the rain attenuation is shared with the light wave system, and the attenuation due to fog and snow is transferred to the millimeter wave system. (2) A light wave millimeter wave complementary communication system is characterized in that line failures caused by fog or snow in light wave communication equipment are backed up by a MiIJm wireless device that has a smaller attenuation margin than the light wave system. A light wave millimeter wave complementary communication system according to claim 1. (3) A light wave communication device and a millimeter wave radio device are installed together, and the light wave system is operated as the main system and the millimeter wave radio system is operated as the secondary, or the millimeter wave radio A light wave millimeter wave complementary communication system according to claim 1, characterized in that a light wave system is mainly operated as a slave system, or a light wave system and a millimeter wave radio system are operated together, and a good line is selected. (4) Installing a millimeter-wave communication device in a frequency band where rainfall attenuation is greater than that of light waves alongside the light-wave communication device, allowing the light-wave system to share the rain attenuation, and the millimeter-wave system to share the attenuation due to fog and snow. Further, a light wave millimeter wave complementary communication system is characterized in that the light wave communication device and the millimeter wave communication device are switched and used based on information indicating the state of a line from a received signal or weather information obtained from a weather sensor.