JP2972432B2 - Radio structure relay system using floating structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio relay system using a floating structure for relaying a radio signal for communication between ground stations via a plurality of aerial stations arranged in the stratosphere, and more particularly to a radio relay in a service area. The present invention relates to a floating structure radio relay system for reducing impossible areas.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication system or the like, a radio wave relay system using a floating structure has been proposed which relays a microwave or millimeter wave frequency radio wave transmitted and received between ground stations via an aerial station installed in the stratosphere. ing. The aerial station is an unmanned airplane (document, P-proc. Of IEEE).
MTT-S International Sym-
Posium, May, 1988. And literature, IEICE Technical Report, SANE89-47,19
90 / May), installed on a floating structure such as an airship or a balloon (patent application, No. 213878, filed on August 13, 1990), and clouds at an altitude of 10 km to 50 km (in the vicinity of Japan). It is held at one point in a quiet atmospheric layer (stratosphere) without fog. The position control energy and the aerial station power of the floating structure are obtained from a flight fuel, a solar cell, and the like held by the floating structure. In the above-mentioned radio relay system, in order to relay radio waves covering a wide service area, a plurality of aerial stations are usually installed, and each ground station transmits and receives radio waves to and from these aerial stations. I do.

Such a radio relay system using a floating structure has a larger service area per station and does not require land for installing a relay station, as compared with a terrestrial system using a radio relay station installed on the ground. It has the advantage of being less susceptible to natural disasters such as earthquakes and typhoons. Also, compared to a satellite communication system that uses a geostationary satellite as a radio relay station, as many radio relay stations as possible can be installed without being bound by orbital allocation under international treaties. Launch costs are low, and radio delay time can be ignored. It has advantages such as easy maintenance.

[0004]

In the above-mentioned conventional radio relay system using a floating structure, a plurality of aerial stations each have a frequency reference generated by a different oscillator. It is difficult to keep the oscillation frequency of the oscillator stable because of the limitations of the above and severe environmental conditions. Therefore, each of the aerial stations must have a frequency reference that satisfies the frequency stability required by the applicable communication system. It was difficult.

Further, in the above-described radio relay system, depending on the frequency of the radio signal transmitted by each air station, the radio signal is transmitted at a specific position determined by the frequency of each radio signal, the transmission power, the arrangement condition of each air station, and the like. When the ground station is installed at this radio interference position, communication between the ground station and the aerial station cannot be performed.

Further, since the aerial station is located at a relatively lower altitude than a satellite, a ground station moving in an urban area, for example, falls behind a building and cannot communicate with any of the aerial stations. Shadowing may occur.

[0007]

According to a first aspect of the present invention, there is provided a radio relay system using a floating structure, wherein the data link signal is transmitted between a reference ground station for transmitting and receiving a data link signal and the reference ground station disposed in the stratosphere. And a ground station for transmitting and receiving the user link signal between the plurality of aerial stations, and a plurality of aerial stations for transmitting and receiving a user link signal obtained by frequency-converting the data link signal. In the relay system, each of the aerial stations generates a carrier signal based on a carrier of a data link signal received from the reference ground station, and uses the carrier signal as a carrier of a user link signal to be transmitted to the ground station. When the carrier frequencies of the user link signals transmitted by the respective aerial stations are offset from each other, interference of radio signals by a plurality of user link signals can be eliminated.

Further, a radio relay system using a floating structure according to a second invention transmits and receives the data link signal between a reference ground station transmitting and receiving a data link signal and the reference ground station disposed in the stratosphere. A plurality of aerial stations for transmitting and receiving a user link signal obtained by frequency-converting the data link signal, and a floating structure using radio relay system including a ground station for transmitting and receiving the user link signal between the plurality of aerial stations, The plurality of aerial stations are N aerial stations in N (N is an integer of 2 or more) directions intersecting linearly starting from a center position of a predetermined service area,
For example, it has a first aerial station offset to the outside of the service area in the east-west direction, and a second aerial station offset to the outside of the service area in the north-south direction starting from the center position of the service area.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a radio wave relay system using a floating structure to which the present invention is applied. The ground station 3, which is a reference station, uses a plurality of ground stations 4a and 4b and a plurality of ground stations 4a and 4b arranged in the stratosphere at an altitude of 10 to 50 km using radio signals having a frequency of about 1 to 100 GHz. connect. The aerial stations 1 and 2 are floated in the stratosphere by a balloon 1a, and their positions are controlled using a solar cell 1b as a power source. The solar cell 1b also supplies power for the wireless transmitting and receiving device 1c. The data link antenna 1d of the aerial station 1 transmits and receives radio signals (data link signals) of, for example, 6 GHz uplink and 4 GHz downlink to and from the ground station 3. On the other hand, user link antenna 1e of aerial station 1 is connected to ground stations 4a and 4a.
2.3 GHz, 2.1 GHz down
The radio signal (user link signal) is transmitted and received. Also,
The wireless transmitting and receiving apparatus 1c converts the 6 GHz signal received by the data link antenna 1d to 2.1 GHz at the illustrated frequency.
z signal, and converts this signal to the user link antenna 1e.
And 2.3 GHz from the antenna 1e.
The signal is converted into a 4 GHz signal and transmitted to the antenna 1d. The aerial station 2 performs the same operation as the aerial station 1.

The radio transmitting / receiving device 1c and the antennas 1d and 1e may be an unmanned airplane or an airship as a floating structure instead of the balloon 1a. The ground stations 4a and 4b may be any of a mobile station, a transportable fixed station, and a fixed station.

FIG. 2 is a block diagram of a first embodiment of the present invention. In the radio wave relay system using the floating structure shown in FIG.
A network management station 6 is provided as the ground station 3 in FIG. 1, and a mobile station 7 is represented as a plurality of ground stations 4a and 4b.

The network management unit (NCU) 6 of the network management station 6
2 receives transmission data such as a call signal from a plurality of user command devices (not shown) corresponding to a plurality of mobile stations (users) 7 and edits the transmission data. The received reception data is distributed to the respective user command devices. Transceiver 61 both transmits the transmit data to a stable signal (e.g. 6GHz band frequency F _CU signal) air station 1 is converted to S1 and the second data link antenna 1d of the carrier frequency, the plurality of antennas 1d from the signal (e.g., frequency F _CD signals 4GHz band) receiving S2 results in the received data from these signals S2. The user command device may be further connected to a public communication line, and may return the received data to the transmission data and retransmit the data.

The radio transceiver 1c of the aerial station 1 receives the signal S1 from the data link antenna 1d at the duplexer 12. This signal S1 is forward link transponder 1
1, the signal (eg, the frequency F _{MDA in the} 2.1 GHz band)
Is converted to S4). The carrier of the signal S4 is created based on the carrier reproduced from the signal S1. The signal S4 is transmitted to the user link antenna 1e via the duplexer 14.
Sent to On the other hand, duplexer 14 (frequency F _MU signal, for example 2.3GHz band) transmitted signal of the mobile station 7 S3
From the antenna 1e. This signal S3 is converted by the return link transponder 13 into the signal S2.

The radio transmitting / receiving device 2c of the aerial station 2 has the same configuration as the radio transmitting / receiving device 1c.
4, the frequency F _{MDB of the} signal S5 transmitted from the signal S4
_Are different from each other. That is, 2.1G transmitted by the plurality of wireless transmission / reception apparatuses 1C to Nc (N is an integer) to the plurality of mobile stations 7 via the user link antenna 1e.
The frequencies of the Hz band signals are offset from each other.

The transmitting / receiving device (T / R) 71 of the mobile station 7
The signals S4 and S5 from the user link antenna 1e
Receiving data to generate the received data, and the terminal device (T
E) The transmission data from 72 is converted into the signal S3 and transmitted to the plurality of antennas 1e. In addition, the terminal device 72
Edits data such as a call signal into the transmission data, and receives the reception data to generate data such as a call signal.

As described above, in the above-mentioned floating body structure radio relay system, the network management station 6 sends a signal S1 of a stable carrier frequency satisfying the conditions of the applied communication system to the aerial stations 1 and 2, and this signal S1 Aerial station 1 which received
The wireless transmission / reception apparatus 1c generates a signal S4 of a stable frequency _{FMDA based on} the reproduction carrier of the signal S1, and receives the signal S1.
Is different from the signal S4 but has a stable frequency F
The signal S5 of the _MDB is generated. Therefore, the radio transceivers 1c and 2c mounted on the aerial stations 1 and 2 can transmit the stable carrier signals S4 and S5 satisfying the requirements of the applied communication system to the mobile station 7.

Further, since the frequencies of the signals S4 and S5 transmitted to the mobile station 7 are offset from each other, the signals do not interfere with each other. Therefore, in the radio relay system using a floating structure having a plurality of aerial stations 1 and 2, communication between the network management station 6 and the mobile station 7 caused by the plurality of aerial stations 1 and 2 using the same carrier is not possible. Eliminating possible areas.

FIG. 3 is a block diagram of the forward link transponder 11 of the radio transmitting / receiving device 1c used in the embodiment of FIG. The signal S1 input from the duplexer 14 to the input terminal 110 is amplified by an amplifier 111 to become a signal S11. A part of the signal S11 is demodulated by a demodulator (DEM) 112 into a baseband signal S12. On the other hand, another part of the signal S12 is divided and the carrier regenerated by the divider (1 / N) 114, is the frequency F _MD signal S14 nearly signal S4. This signal S14 is mixed with a low-frequency signal (frequency ΔF _A ) S16 generated by the oscillator 116 by the frequency converter (MIX) 115, and becomes a carrier signal S15 having a frequency F _MDA (= F _MD + ΔF _A ). . Therefore, the frequency stability of the carrier signal S15 is mainly determined by the frequency stability of the signal S14, that is, the data link signal S1 from the network management station 6. Modulator (MOD)
Reference numeral 113 denotes a carrier signal S15 which is a baseband signal S11.
To produce a signal S13 which is amplified by an amplifier 117 to produce said signal S4 at an output 118.

The signal S1 amplified by the amplifier 111
1 is demodulated by the demodulator 112 to the baseband signal S1.
If the signal S12 is demodulated to an intermediate frequency signal instead of demodulation to 2, and the intermediate frequency signal is further converted to the signal S13, the effect of stabilizing the frequency of the signal S13 is obtained as described above.

Further, forward link transponder 11 of the wireless transmission device 1c also take the same structure as the transponder 11 of FIG. 3, the oscillator 116 produces a signal S16 in different frequency △ F _B to each other with frequency △ F _A, frequency conversion The unit 115 generates a carrier signal S15 having a frequency F _MDB (= F _MD + ΔF _B ).

FIG. 4 is a schematic diagram showing a second embodiment of the present invention. The aerial stations 1, 2, the network management station 6 (not shown) and the mobile station 7 are the same as those shown in the embodiment of FIG.
A predetermined service area 8 of the radio wave relay system using the floating structure includes a city 9. Now, Road 1
When the mobile station 7 moving through the station 0 enters the shadow of the building with respect to any of the air stations 2 and 3, the mobile station 7 and the air stations 1 and 2
, That is, communication between the mobile station 7 and the network management station 6 becomes impossible. Here, the road 10 on the land 9 is often constructed in north-south and east-west directions in Japan. Therefore, in this embodiment, assuming that the city 9 is located at the center point 20 of the service area 8, the aerial station 1 is arranged offset from the service area 8 in the east-west direction outside the service area 8 with the center point 20 of the service area 8 as a starting point. With this arrangement, the mobile station 7
The likelihood of the line of sight between the station and the air station 1 being obstructed by buildings along both sides of the east-west running road 10 is reduced. Similarly, the aerial station 1 is disposed so as to be offset from the service area 8 in the north-south direction with the center point 20 as a starting point, and the line of sight between the mobile station 7 and the aerial station 1 is along both sides of the road 10 running in the north-south direction. To reduce the probability of being blocked by a closed building. When the largest one of the cities 9 in the service area 8 is located away from the center point 20 of the service area 8, the center point 20 may be set as the position of the largest city 9.

As described above, in the embodiment shown in FIG. 4, the aerial stations 1 and 2 are set at the center 20 of the service area 8 in consideration of the arrangement of the roads 10 and buildings of the city 9 in the service area 8.
By placing them in east-west and north-south offsets from (or the center of city 9), only two aerial stations 1
By simply using (2) and (2), the incommunicable area in the service area 8 can be greatly reduced.

[0024]

As described above, the present invention reproduces a reference frequency of an aerial station from a signal having good frequency stability received from a reference earth station, thereby obtaining a frequency stability that satisfies the requirements of an applicable communication system. The signal can be sent to each user ground station such as a mobile station. Further, since the frequency of the transmission signal is made different for each aerial station, radio interference of the transmission signal can be eliminated, and the distance between the user ground station and the aerial station (that is, the reference ground station) can be reduced. The uncommunicable area can be eliminated.

Further, since the aerial stations are arranged offset in N directions, for example, east-west and north-south directions, which intersect linearly from the center of the service area or the metropolis, even if only two aerial stations are used, the aerial stations can be located within the service area. Area where communication between ground stations is impossible can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a radio wave relay system using a floating structure to which the present invention is applied.

FIG. 2 is a block diagram of a first embodiment of the present invention.

FIG. 3 is a block diagram of a forward link transponder 11 in a wireless transmission / reception device 1c used in the embodiment of FIG.

FIG. 4 is a schematic diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1, 2 Aerial station 1a Balloon 1b Solar cell 1c, 2c Wireless transceiver 1d Data link antenna 1e User link antenna 3 Ground station 4a, 4b Ground station 6 Network management station 7 Mobile station 8 Service area 9 City 10 Road 11 Forward link transponder 12, 14 Duplexer 13 Return link transponder 20 Center point 61, 71 Transmitter / receiver (T / R) 62 Network management unit (NCU) 72 Terminal equipment (TE) 110 Input terminal 111, 117 Amplifier 112 Demodulator (DEM) 113 Modulation (MOD) 114 Frequency divider (1 / N) 115 Frequency converter (MIX) 116 Oscillator 118 Output terminal

Continuation of the front page (56) References JP-A-4-96528 (JP, A) JP-A-54-31216 (JP, A) JP-A-64-65472 (JP, A) (58) Fields investigated (Int .Cl. ⁶ , DB name) H04B 7/14-7/195 H04B 7/22

Claims (6)

(57) [Claims] 1. A base station for transmitting and receiving a data link signal, and a base station located in the stratosphere for transmitting and receiving the data link signal and transmitting and receiving a user link signal obtained by frequency-converting the data link signal. In a floating structure-based radio relay system including a plurality of aerial stations and a ground station that transmits and receives the user link signal between the plurality of aerial stations, each of the aerial stations receives from the reference ground station A radio wave relay system using a floating structure, wherein a carrier signal based on a carrier of a data link signal is generated, and the carrier signal is used as a carrier of a user link signal transmitted to the ground station. 2. The radio wave relay system using a floating structure according to claim 1, wherein carrier frequencies of user link signals transmitted by the respective aerial stations are offset from each other. 3. A base station for transmitting and receiving a data link signal, and a base station located in the stratosphere for transmitting and receiving the data link signal and transmitting and receiving a user link signal obtained by frequency-converting the data link signal. In a floating structure-based radio relay system including a plurality of aerial stations and a ground station that transmits and receives the user link signal between the plurality of aerial stations, the plurality of aerial stations are arranged at a center of a predetermined service area. A radio wave relay system using a floating structure, wherein the radio wave relay system is offset outside the service area in each of N (N is an integer of 2 or more) directions that intersect linearly with a position as a starting point. 4. The aerial station, wherein the plurality of aerial stations are orthogonal to the first aerial station offset in one of two orthogonal directions starting from a center position of the service area and outside the service area. 4. The radio relay system using a floating structure according to claim 3, wherein the second aerial station is offset in the other one of the two directions and outside the service area. 5. The air station according to claim 4, wherein the first air station is offset outside the service area in an east-west direction, and the second air station is offset outside the service area in a north-south direction. The radio wave relay system using the floating structure described in the above. 6. The radio wave relay system using a floating structure according to claim 3, wherein a center position of the service area is a position of a largest city in the service area.