JPH11205212A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge a communication range and to reduce the cost of an entire system by heightening a radio transmission frequency for the communication in an area good in a wide field of vision between a base station and a repeater and lowering a radio transmission frequency for the communication between the repeater and a terminal device. SOLUTION: A communication frequency between a base station 1 and a repeater 2 is set to a 60 GHz band and communication frequencies between the repeater 2 and a terminal device 3 and between the repeater 2 and a terminal device 4 are set to a 20 GHz band. The base station 1 adopts a heterodyne system to send/received a radio signal for the 60 GHz band. Therefore, since a radio wave with a frequency band of millimeter wavelength is in general strong in straight advance property, though communication is limited within an area good in a wide field of vision, the disadvantage is mitigated in the case that the base station 1 and the repeater 2 are used semi- fixedly. On the other hand, the radio communication between the repeater 2 and the terminal defice 3 adopts a microwave frequency band whose the frequencies are considerably dropped lower than those of the millimeter wave band so that the communication by using the terminal devices 3, 4 is available even in the outside of an area to be viewed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there is one disclosed in JP-A-8-84106. According to the above document, the conventional wireless transmission system is
The communication between the base station and the terminal device is performed via a microwave repeater. For communication between the base station and the microwave repeater, the communication distance is increased by providing an antenna with strong directivity, and an antenna with weak directivity is used between the microwave repeater and the terminal device. Thus, the communication range is expanded. Since all the microwave repeaters are configured by passive components, amplification and frequency conversion are not performed.

[0003]

However, when the radio transmission frequency is increased and the millimeter wave region is reached, the straightness of the radio wave becomes stronger, so that only communication within the line of sight can be performed. In the prior art described above, since the base station and the repeater are installed semi-fixed on the ceiling of the building, installation within the line of sight is easy, but in the communication between the repeater and the terminal device, There has been a problem in that the possibility of wireless communication being interrupted by an object being placed in the line-of-sight section or by a human being crossing is increased.

In general, the number of terminal devices is usually larger than the number of base stations and repeaters. In order to keep the cost of the entire system low, it is preferable to set the terminal cost as low as possible. However, there has been a problem that the component cost increases as the communication frequency increases, and the cost of the terminal device also increases. The present invention eliminates the above-mentioned problems, and increases the radio transmission frequency for communication in a viewable area between a base station and a repeater, and increases the radio transmission frequency for communication between the repeater and a terminal device. It is an object of the present invention to provide a wireless communication system capable of lowering the communication range to increase the communication range and lowering the cost of the entire system.

[0005]

According to the present invention, there is provided a radio communication system for performing communication between a base station and a terminal device via a repeater. The wireless communication frequency is set higher than the wireless communication frequency between the repeater and the terminal device, and the repeater is provided with frequency conversion means.

[2] In the wireless communication system according to the above [1], the wireless communication frequency between the base station and the repeater is a millimeter wave, and the wireless communication frequency between the repeater and the terminal device is a microwave or less. It is. [3] In the wireless communication system according to [1] or [2], when the heterodyne scheme is adopted for the base station, the intermediate frequency of the base station and the communication frequency of the repeater and the terminal device are the same or different. It is intended to be equivalent.

[4] In the radio communication system according to the above [1], [2] or [3], at least between the base station and the antenna, between the repeater and the antenna, or between the terminal device and the antenna. At least one data transmission means using a coaxial line, a waveguide line, or an optical fiber is provided in one section.

[0008]

Embodiments of the present invention will be described below in detail. FIG. 1 is a schematic diagram of a wireless communication system according to a first embodiment of the present invention. In this figure, 1 is a base station, 1a is an antenna of the base station, 2 is a repeater, 2
a is an antenna of a repeater for transmitting and receiving radio waves from a base station,
2b is an antenna of a repeater for transmitting and receiving radio waves from the terminal device, 3 and 4 are terminal devices, and 3a and 4a are antennas of the terminal device.

FIG. 2 is a block diagram of a repeater of a wireless communication system according to a first embodiment of the present invention. In this figure, 1
2 is a duplexer connected to the antenna 2a;
6, 17, 20 are amplifiers, 14, 18, 24, 25 are filters, 15, 19 are mixers, 21 is a local oscillator, and 22 is a duplexer connected to the antenna 2b. FIG. 3 is a configuration diagram of a base station of a wireless communication system according to the first embodiment of the present invention.

In this figure, 31 is a local oscillator, 32,
35 is a mixer, 33 and 36 are filters, 34 and 37 are amplifiers, and 38 is a transmission / reception switch connected to the antenna 1a. Therefore, the base station 1 is in the millimeter wave band (30 to 300 GHz).
A transceiver for z) is provided, and a heterodyne system using an intermediate frequency as shown in FIG. 3 is employed. Since it is difficult to cover all frequencies in the millimeter wave band with the current technology, a frequency around 60 GHz is used.
The antenna 1a attached to the base station 1 narrows the beam width to enhance directivity.

The repeater 2 performs frequency conversion using mixers 15 and 19 as shown in FIG.
The communication frequency with the terminal device is lower than the communication frequency with the base station. The communication frequency on the terminal device side was set to be lower than the microwave band, that is, lower than 15 GHz. The antenna 2b on the terminal device side is omnidirectional,
Or I chose a type with relatively weak directivity.

Here, the terminal devices 3 and 4 use the technology of the microwave band transceiver which is conventionally used, and can be easily manufactured. As the antennas 3a and 4a of the terminal devices 3 and 4, non-directional or relatively weak directivity type antennas were selected. Hereinafter, the operation of the wireless communication system of this embodiment will be described. In this embodiment, the communication frequency between the base station 1 and the repeater 2 is set to the 60 GHz band, and the communication frequency between the repeater 2 and the terminal device 3 and between the repeater 2 and the terminal device 4 is set to the 2 GHz band.

A heterodyne system is used for transmitting and receiving a radio signal in the 60 GHz band at the base station 1. As shown in FIG. 3, a configuration for realizing this is as follows: radio signals and intermediate frequency signals (IF signals) 40 and 41 using mixers 32 and 35.
Is performed. Since the frequency of the intermediate frequency signals 40 and 41 is set to the 2 GHz band in accordance with the communication frequency of the repeater 2 and the terminal devices 3 and 4, the frequency of the local oscillator 31 is 58 GHz.
Hz.

When a signal in the 2 GHz band is input to the IF input signal 40, the output of the mixer 32 has a transmission frequency of 60 GHz.
The z band, the 56 GHz band of the image frequency, and other spurious signals are output. In the filter 33, only the required transmission frequency band of 60 GHz is passed, and the signal is amplified by the amplifier 34 and then output as a radio signal from the antenna 1a. Switching between transmission and reception is performed by a transmission / reception switch 38.

The received signal is input from the antenna 1a, passes through the transmission / reception switch 38 and the amplifier 37, and then passes only the intended 60 GHz band by the filter 36. This signal is
5 is converted to an IF output signal 41 of 2 GHz. The antennas 1a and 2a between the base station 1 and the repeater 2 narrow the beam width and increase the antenna gain to increase the communication distance. In addition, since the millimeter wave radio wave has the property of being less diffracted and having high straightness, the two antennas 1a and 2a are installed in line of sight so that no obstacles enter between the antennas.

The repeater 2 performs frequency conversion between the 60 GHz band which is the transmission / reception frequency on the base station 1 side and the 2 GHz band which is the transmission / reception frequency on the terminal devices 3 and 4 side. Its configuration is shown in FIG.
As shown in (1), frequency conversion is performed using the mixers 15 and 19. The operation principle is the same as that of the frequency conversion in the base station 1, and the description of the operation is omitted. However, according to this, the frequency of the local oscillator 21 needs to be set to 58 GHz in order to perform this frequency conversion. The station oscillator 21 uses the same components as the station oscillator 31 of the base station 1.

Further, the amplifier 13, the filter 14, the mixer 15, the amplifier 17, the filter 18, and the mixer 19 are also the amplifier 37, the filter 36, and the mixer 3 used in the base station 1.
5, common components were used for the amplifier 34, the filter 33, and the mixer 32, respectively. In addition, as the antenna between the repeater 2 and the terminal device 3, a non-directional or weakly directional antenna was selected. Frequencies near this are widely used in mobile phones, etc., and have less straightness than millimeter waves.
The terminal can be used in a place that is not within the line of sight, such as in a building or a car. The configuration of the antenna and terminal,
It can be easily realized by using the technology.

As described above, according to the first embodiment, in the wireless transmission in the relay section between the base station 1 and the repeater 2, the communication data of all the plurality of terminal devices are concentrated, and large-capacity communication is required. However, in this embodiment, by increasing the radio frequency in the relay section sufficiently higher than the radio frequency on the terminal side, the transmission data in the relay section is increased in capacity. Further, since a high frequency of a millimeter wave is used in the relay section, it is possible to transmit a very large amount of data.

In general, the frequency of the millimeter wave band has a drawback that the communication range is limited within the line of sight because the directivity of the radio wave is strong, but the base station 1 and the repeater 2 are semi-fixed as in this embodiment. The disadvantages are also alleviated when used in. on the other hand,
In the wireless communication between the repeater 2 and the terminal device 3, the terminal devices 3 and 4 are used outside the line of sight by using the microwave band with a frequency significantly lower than the millimeter wave band in the relay section. And the convenience is greatly improved as compared with the case where a frequency in the millimeter wave band is used. In addition, technology development of microwave band components is progressing, and it can be obtained cheaper than millimeter band components,
The cost of the terminal devices 3 and 4 can be reduced.

Further, in this embodiment, the base station 1
And the communication frequency between the repeater 2 and the terminal devices 3 and 4 are set to be the same, so that the base station 1 and the repeater 2 can share components such as a station oscillator, a mixer, and a filter. Therefore, the cost can be reduced. However, actually, even if the same frequency is set by using a common component for the station oscillator 31 of the base station 1 and the station oscillator 21 of the repeater 2, the station oscillators 31 and 21 are not synchronized with each other. Therefore, the frequencies do not become completely equal, and there is some error.

Therefore, for such a reason, the intermediate frequency of the base station 1 and the communication frequency between the repeater 2 and the terminal devices 3 and 4 may not be the same and may be shifted to some extent. If small, this effect will not be impaired. Therefore, if the intermediate frequency of the base station 1 and the communication frequency between the repeater 2 and the terminal devices 3 and 4 are the same or equivalent, this result can be expected.

The present invention can be used for mobile band communication and data communication such as LAN. Next, a second embodiment of the present invention will be described. In the first embodiment, the millimeter wave radio is used in the relay section between the base station 1 and the repeater 2. However, as the frequency increases, the free space loss increases, so that long-distance transmission becomes difficult. Further, as the frequency becomes higher, it becomes more difficult to produce a high-output amplifier, so that long-distance transmission becomes more difficult. The second embodiment solves the problem.

FIG. 4 is a schematic diagram of a wireless communication system according to a second embodiment of the present invention. As shown in this figure, a waveguide 52 and an E / O converter 5 are provided between a base station 51 and an antenna 56.
3. An optical communication section comprising an optical fiber 54 and an O / E converter 55 is provided, and a coaxial line 58 is provided between the repeater 59 and the antenna 57.

The other parts are basically the same as in the first embodiment. Next, the operation of the second embodiment will be described. As shown in FIG. 4, the millimeter wave output from the base station 51 propagates through the waveguide 52. This signal is converted into light by the E / O converter 53, sent to the optical fiber 54, and
The signal is converted into an original electrical signal by the / E converter 55 and output from the antenna 56 as a wireless signal.

This radio signal is captured by an antenna 57, passes through a coaxial line 58, and is input to a repeater 59. Thus, according to the second embodiment, the transmission loss of the waveguide is 6
Since it is as small as several dB / km or less at 0 GHz, it is advantageous for long-distance transmission. In addition, about 0.2 dB for optical fiber
/ Km is possible, so that long-distance transmission can be realized. As in this embodiment, transmission of a signal in the 60 GHz band using an optical fiber has already been reported in trial production examples and experimental results, and is not difficult to realize.

Although the loss of the coaxial line is a large loss in this frequency band, it can be freely bent unlike a waveguide or the like, so that its usefulness is great. If the antenna 57 is not in the line of sight, the antenna 57 can be set in the line of sight by providing the coaxial line 58. As described above, the base station 51
By laying the waveguide 52, the coaxial line 58, and the optical fiber 54 between the antenna 56, the repeater 59, and the antenna 57, the distance between the base station 51 and the repeater 59 can be greatly increased. .

The same embodiment and effect can be applied between the repeater 59 and the antenna 60, between the terminal device 62 and the antenna 61, and between the terminal device 64 and the antenna 63. This embodiment can also be used for mobile band communication and data communication such as LAN. It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the gist of the present invention.
They are not excluded from the scope of the present invention.

[0028]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the invention, the communication range can be expanded and the cost of the entire system can be reduced.

(2) According to the second aspect of the present invention, in the wireless transmission in the relay section between the base station and the repeater, communication data of all the plurality of terminal devices is concentrated, and large-capacity communication is required. However, according to the present invention, by increasing the radio frequency in the relay section sufficiently higher than the radio frequency on the terminal side, the transmission data in the relay section is increased in capacity. Further, since a high frequency of a millimeter wave is used in the relay section, it is possible to transmit a very large amount of data.

In general, the frequency in the millimeter wave band has a drawback that the communication range is limited within the line of sight due to the strong straightness of radio waves. However, the base station and the repeater are semi-fixed as in the present invention. In some cases, the disadvantages are alleviated. On the other hand, in the wireless communication between the repeater and the terminal device, the use of the microwave band by drastically lowering the frequency than the millimeter band in the relay section makes it possible to use the terminal device even outside the line of sight. However, the convenience is remarkably improved as compared with the case where the frequency in the millimeter wave band is used.

Further, the technology development of microwave band components is progressing, and the components can be obtained at a lower price than the millimeter wave band components, so that the cost of the terminal device can be reduced. (3) According to the third aspect of the present invention, since the intermediate frequency of the base station and the communication frequency between the repeater and the terminal device are set to be the same, a station oscillator, a mixer, a filter, and the like are used in the base station and the repeater. Parts can be shared and cost can be reduced.

However, in practice, even if the same frequency is set by using common parts for the station oscillator of the base station and the station oscillator of the repeater, the station oscillators are not synchronized with each other. , And has some error. Therefore, for such a reason, the intermediate frequency of the base station and the communication frequency between the repeater and the terminal device may not be the same, and may be shifted to some extent. It will not be compromised.

Therefore, if the intermediate frequency of the base station and the communication frequency between the repeater and the terminal device are the same or equivalent, this result can be expected. (4) According to the invention of claim 4, since the transmission loss of the waveguide is as small as several dB / km or less at 60 GHz, it is advantageous for long-distance transmission. In addition, about 0.2
Since the loss can be as low as dB / km, long-distance transmission can be further realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a wireless communication system according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a repeater of the wireless communication system according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a base station of the wireless communication system according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a wireless communication system according to a second embodiment of the present invention.

[Explanation of symbols]

 1,51 base station 1a base station antenna 2,59 repeater 2a, 2b repeater antenna 3,4,62,64 terminal device 3a, 4a terminal device antenna 12,22,38 duplexer 13,16, 17, 20, 34, 37 Amplifier 14, 18, 24, 25, 33, 36 Filter 15, 19, 32, 35 Mixer 21, 31 Local oscillator 40, 41 Intermediate frequency signal (IF signal) 52 Waveguide 53 E / O converter 54 Optical fiber 55 O / E converter 56, 57, 60, 61, 63 Antenna 58 Coaxial line

Claims (4)

[Claims] In a wireless communication system for communicating between a base station and a terminal device via a repeater, a wireless communication frequency between the base station and the repeater is set higher than a wireless communication frequency between the repeater and the terminal device. A wireless communication system, wherein the repeater is provided with frequency conversion means. 2. The wireless communication system according to claim 1, wherein a wireless communication frequency between the base station and the repeater is a millimeter wave, and a wireless communication frequency between the repeater and the terminal device is a microwave or less. A wireless communication system, comprising: 3. The wireless communication system according to claim 1, wherein, when the heterodyne system is adopted for the base station, an intermediate frequency of the base station and a communication frequency of the repeater and the terminal device are the same or equivalent. A wireless communication system characterized in that: 4. The wireless communication system according to claim 1, 2 or 3, wherein at least one section is provided between the base station and the antenna, between the repeater and the antenna, or at least one section between the terminal device and the antenna. A wireless communication system comprising at least one data transmission means using a line, a waveguide line, or an optical fiber.