JPH0576213B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention uses shared polarized waves for communication between mobile stations on the ground or between a mobile station and a fixed station via a repeater mounted on a geostationary satellite. The present invention relates to a polarization sharing transmitter/receiver for a mobile station in a multi-beam mobile satellite communication system.

"Prior Art" FIG. 6 shows the zone of a link (mobile link) between a mobile station and a geostationary satellite in a conventional multi-beam mobile satellite communication system. The service area is divided into a plurality of zones 10, and a mobile station 11 moves between these zones 10. The numbers in the zone 10 are numbers assigned to each zone, such as assigned frequencies, and right-handed or left-handed circularly polarized waves are uniformly used. The configuration of the transmitter/receiver of the mobile station 11 is shown in FIG. The circularly polarized wave radiating element 12 is connected to a diplexer 13, and a transmitting circuit 14 and a receiving circuit 15 are connected to the diplexer 13.

Conventionally, a portion of the UHF, L-band, and S-band frequency bands have been allocated to mobile links of this type of satellite communication system. These allocated bandwidths are not wide enough to meet expected future demand, so we aim to increase the number of channels accommodated by configuring regionally divided zones as shown in Figure 6 to reuse frequencies. A multi-beam system has been considered and is being put into practical use in many countries. Regarding polarization, in order to reduce deterioration in line quality due to rotation of polarization due to the surrounding environment on the propagation path or on the receiving side, circular polarization is used, and only one polarization is used. Even if the mobile station moves to a zone irradiated with another beam, there is no need to switch the polarization used. Therefore, the transmitter/receiver of the mobile station is not configured to automatically switch the polarization used as the mobile station moves between zones, as shown in FIG.
At this time, the premise of frequency allocation for each beam is to allocate the same frequency approximately at intervals of two beams, taking into account the radiation pattern of the antenna onboard the satellite, in order to suppress the amount of interference between beams that use the same frequency. It has become normal.

``Problem to be solved by the invention'' If demand increases further in the future, there will be a demand for changing the repetition of the same frequency from the conventional 2-beam spacing to 1-beam spacing in order to make even more effective use of limited frequency resources. arise. One effective way to achieve this without increasing the amount of inter-beam interference is to use mutually different polarizations between beams that are closest to each other among beams that use the same frequency. At this time, since either right-handed or left-handed polarization is assigned to each zone, the mobile object must select the polarization assigned to the destination zone when moving to another zone. Moreover, this selection function needs to be automated in preparation for receiving and responding to incoming call signals that occur irregularly.

As described above, when sharing polarized waves, an automatic polarization selection function is required, which is inconvenient with conventional mobile station transmitter/receiver technology that transmits and receives only one polarized wave.

This invention was made to solve the above-mentioned problems, and in a multi-beam mobile satellite communication system that shares polarization, it is possible to specify either right-handed or left-handed polarization for each wireless zone of the mobile link. An object of the present invention is to provide a polarization shared transmitter/receiver for a mobile station that can automatically detect and select a designated polarization of the zone in which the mobile station is located.

"Means for Solving the Problems" A polarization shared transmitter/receiver for a mobile station for mobile satellite communication according to the present invention includes a circularly polarized wave radiating element capable of selectively receiving both polarized waves, and a polarized wave transmitting/receiving device for a mobile station in mobile satellite communication. Equipped with radio equipment consisting of an antenna system consisting of a power supply switching circuit for switching waves, a reception strength comparison circuit, and other transmitting/receiving circuits, this enables reception of calls in one or more zones where a mobile station may be located. This system is designed to receive paging and other control channel signals, to specify the zone where they are located, and to set the transmitting and receiving polarization to the designated polarization of that zone.

"Operation" The polarization shared transmitter/receiver for a mobile station for mobile satellite communication according to the present invention is provided with a circularly polarized wave radiating element and a power feeding switch for switching the relative phase between two feeding points of the radiating element. Alternatively, by arranging a polarizer as a polarization radiating element and having a linearly polarized primary radiating element that can selectively radiate both horizontal and vertical polarized waves as a feed switch, it is possible to select between right-handed and left-handed circularly polarized waves. Then, incoming calls and other control channel signals of one or more zones where the mobile station may be located are received by the antenna circuit and the receiving circuit, respectively, and the reception strength is compared by the reception strength comparison circuit to determine the zone where the mobile station is located. It specifies the zone and sets the transmitting and receiving polarization to the specified polarization for that zone.

Embodiment FIG. 1 shows an embodiment of the present invention, and parts corresponding to those in FIG. 7 are given the same reference numerals. A 90° hybrid 16 is connected to the circularly polarized wave radiating element 12,
A power supply switch 17 is connected between the 90° hybrid 16 and the diplexer 13, and a reception strength comparison circuit 18 is connected to the reception circuit 15.

When the right-handed circularly polarized wave (RHCP) enters the circularly polarized wave radiating element 12, the R of the output end of the 90° hybrid 16
The output appears on the L side of the 90° hybrid 16 when a left-handed circularly polarized wave (LHCP) is incident. The 90° hybrid 16 is for feeding power to the feeding points of the circularly polarized wave radiating element 12 with a mutual phase of ±90°. The power supply switch 17 is operated by the polarization selection control signal from the reception strength comparison circuit 18.
This is to connect either the R or L feeding end of the 90° hybrid 16 to the transmission/reception system;
Transmission and reception polarization can be determined by selecting . The diplexer 13 is for sharing one antenna for transmission and reception. The transmission circuit 14 modulates, frequency converts, and amplifies the transmission input. The receiving circuit 15 demodulates each carrier frequency and outputs the signal strength thereof. The reception strength comparison circuit 18 outputs a polarization switching control signal for operating the power supply switch 17, and also monitors and compares the reception strength signal output from the reception circuit 15.

In the zone configuration example shown in FIG. 5, when a mobile station moves from one zone to an adjacent zone, the first
The operation of the illustrated embodiment will be explained. In addition, in FIG. 5, R and L mean the designated polarization of the zone.

When the mobile station 11 moves beyond the boundary area with an adjacent zone, the reception strength of the mobile station 11 decreases below the reference level, and the reception strength comparison circuit 18 detects that the mobile station 11 is moving between zones. Note that the received waves at this time can be radio waves of incoming calls and other control channel signals emitted from satellites for each zone. In order to identify which of the multiple zones adjacent to the zone in which it was previously located, i.e. the frequency band and polarization assigned to that zone, Radio waves of incoming calls and other control channel signals are sequentially received by combining their assigned frequencies and polarizations. At this time, the polarization is determined by switching the polarization of the circularly polarized wave radiating element 12 by the operation of the feeding switch 17 in accordance with the polarization switching control signal of the reception strength comparison circuit 18, and the frequency is determined by switching the polarization of the circularly polarized wave radiating element 12.
The switching is performed by changing the local oscillation frequency of No. 5, etc. As a result, the reception strength comparison circuit 18 detects the combination of frequency and polarization when the reception strength is the strongest, specifies the location zone, and selects the specified polarization.

In the above embodiment, the case where one circularly polarized wave radiating element is shared for transmitting and receiving is shown, but as shown in Fig. 2,
By making one circularly polarized wave radiating element for reception only and the other circularly polarized wave radiating element for transmission only, the die replexer 13 is unnecessary, and the same effect can be obtained by placing the feed switch 17 in both the transmission and reception systems. It will be done.

Also, as shown in the embodiment of Fig. 3, a polarizer 1 is used instead of a circularly polarized wave radiating element and a 90° hybrid.
9 and the linearly polarized wave radiating element 21, and the feeding end of the linearly polarized wave radiating element 21 is switched by the feeding switch 17 to switch the polarization of the linearly polarized wave radiating element 21. Effects can be obtained.
As specific examples of the polarizer 19 shown in FIG. 3, FIG. 4 shows examples of a meander line polarizer 19a and a cross dipole polarizer 19b. The meander line polarizer 19a has a conductor pattern formed on a dielectric substrate, as shown in FIG. It is designed to have a 90° phase difference between the waves, so it works as a converter between circularly polarized waves and linearly polarized waves. In other words, a linearly polarized wave with a polarization plane making an angle of 45° with respect to the direction along the crank-shaped conductor line is called right-handed polarized wave, while a linearly polarized wave with a polarization plane making an angle of 135° with respect to the direction along the crank-shaped conductor line is called left-handed polarized wave. Convert.
In Fig. 3, V means the former linearly polarized wave and its feeding end, H means the latter linearly polarized wave and its feeding end, R means right-handed circularly polarized wave, and L means left-handed circularly polarized wave. means. Also, cross dipole polarizer 1
9b, an example of which is shown in FIG. 4b, has a phase difference of 90° between one dipole and the other dipole, and has the same effect as the meander line polarizer.

"Effects of the Invention" As described above, according to the present invention, a mobile station can
Since either right-handed or left-handed polarization assigned to the zone in which the mobile station is located is automatically selected, even when a mobile station moves between zones in a multi-beam mobile satellite communication system that uses shared polarization. It has the effect of contributing to smooth communication by automatically continuing to be able to transmit and receive, and is therefore superior to the effective use of frequencies compared to conventional mobile satellite communication systems that use only one polarization. This has the great effect of facilitating the introduction of a multi-beam mobile satellite communication system that uses shared polarization.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of this invention, Fig. 2 is a block diagram showing another embodiment of this invention, and Fig. 3 is a circularly polarized wave radiating element in this invention and its radiating element. A diagram showing another example of power feeding,
Fig. 4 is a diagram showing a specific example of the polarizer in Fig. 3, Fig. 5 is a diagram showing a zone configuration of a mobile satellite communication system when polarization is shared, and Fig. 6 is a diagram showing a conventional mobile satellite communication system. FIG. 7 is a diagram showing a conventional mobile station transmitting/receiving device.

Claims (1)

[Claims] 1. A receiving circuit that demodulates each carrier frequency and outputs the signal strength corresponding to a radio frequency band assigned to each zone of a mobile link, and a receiving circuit that demodulates a modulated wave of voice or data to a carrier frequency. A transmitting/receiving device for a mobile station for mobile satellite communications, which is equipped with a variable and an amplifying transmitting circuit, a circularly polarized wave radiating element that selectively radiates both right-handed and left-handed polarized waves, and the circularly polarized wave radiating element. and a feed switching device placed between the circularly polarized wave radiating element and the receiving circuit and the transmitting circuit so as to switch the relative phase between the two feeding points, and comparing each receiving intensity output of the receiving circuit. A reception strength comparison circuit is provided, and these receive and compare incoming calls and other control channel signals in one or more zones in which the mobile station may be located, identify the zone in which the mobile station is located, and determine the transmitting and receiving polarization. A polarization shared transmitter/receiver for a mobile station in mobile satellite communication, characterized in that the polarization is set to a designated polarization of a zone. 2. The polarization shared transmitting/receiving device for a mobile station for mobile satellite communication according to claim 1, wherein the feed switching device is disposed between a circularly polarized wave radiating element used for both transmission and reception and a diplexer. 3. The circularly polarized wave radiating element is provided for transmission and for reception, and the first feed switch is provided between the circularly polarized wave radiating element for transmission and the transmitting circuit,
2. The polarization shared receiving device for a mobile station for mobile satellite communication according to claim 1, wherein the second feed switching device is provided between the receiving polarized wave radiating element and the receiving circuit. . 4. Claim 1 or 2, characterized in that the circularly polarized wave radiating element is provided with a polarizer, and the feed switching device is provided with a linearly polarized primary radiating element that selectively radiates both horizontal and vertically polarized waves. 3. The polarization shared receiving device for a mobile station for mobile satellite communication according to 3.