JP2003332966A - Circuit connection method, system, and terrestrial station for satellite communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a satellite communication circuit with ease which promotes efficient use of the circuit without requiring complex control of circuit connection by DAMA device or the like. <P>SOLUTION: This circuit connection method for satellite communication is used for a satellite communication system. In this method, a frequency band of a transponder loaded on a satellite station is divided into a plurality of communication channels by a code division system, and a plurality of terrestrial stations of the channels use them as satellite communication circuits. When one of the terrestrial stations requests connection to one of the channels, power density of the transponder on the satellite is measured. If the density is higher than an allowable value, use of the circuit by the terrestrial station which requested the connection is restricted. If it is lower than the allowable value, use of the circuit by the requested terrestrial station and its distant terrestrial station is authorized. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line control technique for a satellite communication system, and involves complicated processing such as call control based on allocation of a satellite communication line by a control station (master station) and monitoring of the number of channels used. The present invention relates to a satellite communication line connection method, a satellite communication system, and a communication device therefor that can easily set up a satellite communication line between each earth station (slave station).

[0002]

2. Description of the Related Art Conventionally, PAMA (Pre-Assignment Mul) has been used as an access method in satellite communication.
triple Access: Hereinafter referred to as PAMA method. ), Or DAMA (Demand Assig)
nment Multiple Access: Below, D
It is called the AMA method. ) Called multiple access method is widely used. The former is suitable for large bundle lines because it allocates frequency, time, code, etc. to each communication partner in advance according to the amount of communication, and the latter is suitable for large bundle lines. It is a method that is released each time and is suitable for small bundle lines.

For multiple access in satellite communication, FDMA is used.
There are three types of systems called (frequency division multiple access), TDMA (time division multiple access), and CDMA (code division multiple access), which are required communication capacity, frequency band, satellite station power, earth station scale, and radio. It is decided which method to use in consideration of the type of line.

The transmission capacity of a communication satellite (satellite station) is
It is determined by the number of transponders mounted on the satellite station and the frequency band thereof, and it is desirable to mount a large number of wideband transponders because the cost per line can be suppressed as the transmission capacity increases. Broadband ones such as 36 MHz and 54 MHz are used.

[0005]

However, since the conventional satellite communication line connection system is configured as described above,
There were the following issues. For example, in the line connection by the DAMA system, since a limited number of relay lines are used by a large number of earth stations, the earth station serving as a master station has a satellite communication circuit line allocation device called a DAMA control device (hereinafter, referred to as DMA control device).
It is called an AMA device. ) Is provided, the line use status of the relay line is constantly managed by this DAMA device, and if there is a request for a new line connection, a complicated line connection control such as allocating a line by designating an empty line is required. However, there is a problem in that it takes a long time to establish a line and that the earth station placed on the ground becomes expensive due to the necessity of providing such a line allocation device.

On the other hand, in the line connection according to the PAMA method, since the line portion corresponding to the communication amount is fixedly assigned in advance for each communication partner, complicated line connection control like the DAMA method is unnecessary. However, there is a problem in that there are many unused unused lines, which is inefficient.

Further, as described above, by mounting a plurality of wideband transponders on the satellite station, it is possible to increase the number of lines that can be relayed by the satellite station and to suppress the cost per line. As the number of lines that can be relayed increases due to the, the control of the line allocation by the DAMA device becomes more complicated in the DAMA method, and the number of unused lines that are not used in the PAMA method increases and becomes inefficient. Will be things.

The present invention has been made in order to solve the above problems, and efficiently uses a relay line relayed by a satellite station in spite of an increase in the number of relay lines relayed by the satellite station. While the DAMA device is installed,
A new satellite communication line connection system, satellite communication system, and communication therefor which can easily set a satellite communication line between each slave station without controlling a complicated line connection for line allocation etc. by an AMA device The purpose is to provide a device.

[0009]

A satellite communication line connection method according to the invention of claim 1 divides a frequency band of a repeater mounted on a satellite station into a plurality of communication channels by a code division method, A satellite communication line connection method of a satellite communication system used as a satellite communication line by a plurality of earth stations of a communication channel, which is mounted on the satellite station when any one of the earth stations requests a connection to the communication channel. Measured the power density of the relay device, and when the power density is equal to or more than the allowable value, the use of the satellite communication line of the earth station that has made the connection request is restricted, and the power density is smaller than the allowable value. In some cases, the use of the satellite communication line is permitted by the earth station that has made the connection request and the earth station that is a communication partner of the earth station.

A satellite communication system according to a second aspect of the present invention includes a satellite station equipped with a repeater, and a plurality of earth stations requesting connection of a satellite communication line by a code division multiple access system via the satellite station, The power density of the repeater mounted on the satellite station is measured through a common control line shared by the plurality of earth stations, and the satellite station is measured when the measured power density of the repeater is not less than an allowable value. The earth station that has requested the connection of the satellite communication line via the limit signal for restricting the connection of the satellite communication line, and when the measured power density of the repeater is smaller than the allowable value An earth station that has requested a satellite communication line connection via the control station and a control station that notifies the earth station that is the communication partner of the satellite communication line of a permission signal that permits the connection of the satellite communication line. Station Has a spreading code table consisting of a plurality of spreading codes set to, while transmitting the spread signal spread by the spreading code of its own station to the communication partner based on this spread code table, while receiving the received signal from the communication partner. It is reproduced by the spread code of the communication partner.

A satellite communication system according to a third aspect of the present invention includes a satellite station equipped with a repeater, and a plurality of earth stations requesting connection of a satellite communication line by a code division multiple access system via the satellite station, The power density of the repeater mounted on the satellite station is measured via a common control line shared by the plurality of earth stations and shared by the plurality of earth stations. A power density determination device that determines that the satellite communication line cannot be connected, and determines that the satellite communication line can be connected when the measured value is smaller than the allowable value, and the satellite communication lines from the plurality of earth stations. And a control station that notifies the information of the earth station that has made this connection request to the earth station that is the communication partner, and the plurality of earth stations responds to the determination of the power density determination device. While making a connection request for the satellite communication line, and while transmitting a spread signal spread by the spread code of the own station based on a spread code table consisting of a plurality of spread codes set for each earth station, to the communication partner, The received signal from the communication partner is reproduced by the spread code of the communication partner.

In a satellite communication system according to a fourth aspect of the present invention, the earth station stores a spread code table notified from the control station via the satellite station.

A satellite communication earth station according to the invention of claim 5 is
A satellite communication line connection request is made by the code division multiple access method via a common control line shared by multiple satellite communication earth stations, and communication with other earth stations is made by the satellite communication line set based on this connection request. In the satellite communication earth station, the radio wave signal is transmitted to another earth station which is a communication partner via the satellite station, and the radio wave signal which is transmitted from the other earth station which is a communication partner is received via the satellite station. A transmitting / receiving antenna, a receiving unit for receiving and processing a radio signal received by the transmitting / receiving antenna, and a spread code table storage unit for storing a spread code table made up of a plurality of spread codes assigned to each of the plurality of earth stations. , A received signal that has been received and processed by the receiving unit using the spreading code of the other earth station that is the communication partner based on the spreading code table stored in the storage unit. It applies despread processing to, in which a demodulating means for reproducing the original communication signal.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to FIGS. 1 to 4.
1 is a system schematic diagram schematically showing a satellite communication system according to Embodiment 1 of the present invention, and FIG. 2 is an embodiment of the present invention used as a satellite communication earth station of a satellite communication system as shown in FIG. 1, for example. FIG. 3 is a block diagram showing a satellite communication earth station according to mode 1; In FIG. 1, reference numeral 1 is a satellite station equipped with a repeater (not shown) of a satellite communication line called a transponder, 2-1 to 2-n (n is 1).
The above integers are so-called code division multiple access methods (hereinafter,
It is called a CDMA system. The satellite communication earth station (hereinafter referred to as the earth station) for setting the satellite communication line with another satellite earth station by), 3 is a request for connection from each of the plurality of earth stations 2-1 to 2-n. In response to this, the control station 4 which notifies the restriction or permission of the setting of the satellite communication line according to the power density of the repeater mounted on the satellite station 1 is a control signal of the modulation signal from the satellite station 1 received by the control station 3. The power density of the repeater installed in the satellite station 1 is measured from the received power, and whether or not the satellite communication line can be set up as described later based on the measured value of the power density and the preset allowable value of the power density. Of the power density measuring device 5 for judging each of the earth stations 2-1 to 2-2
n is a terminal device such as a telephone connected to the control station 3 and the like via the communication line 6.

Generally, in the CDMA system, a special code called a spreading code is prepared for each channel, and the transmitting side spreads the signal to be transmitted to the receiving side by using the spreading code and transmits it, and the receiving side. The original signal is reproduced by demodulating using the same spreading code as that used for the transmission signal or the spreading code. That is, the receiving side can reproduce the information transmitted from the transmitting side by performing demodulation processing using the spreading code if the spreading code used on the transmitting side is known, and the transmitting / receiving side can perform time division. It is possible to communicate with each other without frame synchronization and channel synchronization as in the multiple access method.

Each of the earth stations 2-1 to 2-n constituting the satellite communication system as shown in FIG. 1 is a fixed earth station, or a mobile earth mounted on a moving body such as an aircraft or a ship. Any of the stations may be used, and a satellite communication system including both the fixed station and the mobile type may be configured.

Reference numeral 7 denotes each earth station 2-via the satellite station 1.
1 to 2-n and the control station 3 share the line connection request signal transmitted to the control station 3 from each of the earth stations 2-1 to 2-n, or from the control station 3 to each of the earth stations 2.
-1 to 2-n, a pair of common control lines for limiting the setting of satellite communication lines / carrying permission signals, and the like, 8 is an earth station 2 set based on the permission signal notified from the control station 3. -1 and the earth station 2-2 are satellite communication lines.

The frequency bands of radio waves used as communication lines for satellite communication are 1.6 GHz / 1.5 GHz (L band), 6 GHz / 4 GHz (C band), 8 GHz / 7.
Although there are GHz (X band), 14 GHz / 12 GHz (Ku band), 30 GHz / 20 GHz (Ka band), etc., in the satellite communication system according to the first embodiment,
An optimum frequency band is appropriately used according to the required communication capacity, frequency band, power of satellite station 1, scale of earth station, characteristics (use) of satellite communication line, and the like. Generally, the larger the transmission capacity of the transponder, the lower the cost per line, but if the number of users of the line is small, the number of free communication channels will increase, resulting in an inefficient system. Determine the frequency band to use.

Recently, a frequency band higher than the Ka band,
For example, 50 GHz / 40 GHz is also being developed to meet the next-generation demand for large capacity and wide band. In the satellite communication system, due to the relationship with the electric power of the satellite station 1, the uplink from each earth station to the satellite station 1 has a higher frequency band in which the radio wave attenuation is larger, Use the lower frequency band with less attenuation for the downlink to 2-1 to 2-n.

In FIG. 2, reference numeral 9 is a transmission / reception antenna for transmitting a radio wave signal to the satellite station 1 and receiving the radio wave signal transmitted from the satellite station 1, 10 is a transmission / reception switch such as a circulator, and 11 is a transmission. A transmitter having a frequency converter, a large power amplifier, etc., 12 is a receiver having a receiver frequency converter, a low noise amplifier, etc., 13a is also used for the common control line 7 and the satellite communication line 8, and is used for primary modulation. The modulation means for performing the spreading process or the like by the spreading code of its own station on the generated communication signal, 13b is also used as the common control line 7 and the satellite communication line 8 similarly to the modulation means 13a, and the communication signal received by the receiving unit 12 is processed. , Demodulation means for performing despreading processing using the spreading code of the communication partner, and further performing demodulation processing and the like to reproduce the original communication signal.
3b is instructed to switch to the setting for the common control line 7 or the setting for the communication line 8, respectively, and for the modulation means 13a, the spread processing of the transmission signal by the spread code previously assigned to the own station, and the demodulation means 13b. On the other hand, the line control means for instructing the despreading processing of the received signal by the spreading code assigned to the communication partner, and the reference numeral 15 is a unique one previously assigned to each of the earth stations 2-1 to 2-n as described above. A spread code table storage unit that stores a spread code table composed of spread codes, and 16 is an interface device having a switching function to which a plurality of terminal devices 5 are connected.

The spread code table storage unit 15 of each of the earth stations 2-1 to 2-n has a unique spread code previously assigned to each of the earth stations 2-1 to 2-n as shown in FIG. Each of the earth stations 2-1 to 2-n performs a spreading process or a despreading process of a communication signal based on the spreading code table 17 (for example, the earth station). The spreading code C1 is assigned to 2-1 and the spreading code Cn is assigned to the earth station 2-n. Each earth station 2-1 to 2-n performs spreading processing using the spreading code of its own station, and Despread processing using the spreading code of the communication partner is performed on the communication signal from the communication partner subjected to the reception processing. When the number of earth stations 2 forming the satellite communication system changes due to expansion or contraction of the communication area, a new spreading code table is updated in the spreading code table storage unit 15 each time. And use.

For example, each time there is a change in the contents of the spread code table, the control station 3 transmits a new spread code table to each of the earth stations 2-1 to 2-n, and each of the earth stations 2-1 to 2n. By automatically updating the new spreading code table received in -n, even if the number of earth stations 2 forming the satellite communication system is changed, the changed code can be relatively easily changed. The operation of the system can be started.

Next, the operation of the satellite communication system according to the first embodiment, particularly the connection of the satellite communication lines by the earth stations 2-1 to 2-n and the control station 3 will be described in detail. Since each of the earth stations 2-1 to 2-n has the same configuration, the earth station 2-1 and the earth station 2-2 are shown here.
I will explain the setting of the satellite communication line between
It is assumed that the earth station 2-1 makes a line connection request to the control station 3. Each of the earth stations 2-1 to 2-n is connected to the control station 3 via the common control line 7 in the communication standby state, and the earth station 2-1 first sends the line connection request signal via the common control line 7. To send. This line connection request signal includes the source information of the local station that is the source and the destination information of the earth station 2-1 that is the communication partner.

The line connection request signal transmitted from the earth station 2-1 is relayed by the satellite station 1 and received by the control station. At the control station 3 side, the satellite station 1 received by the control station 3
A power density measuring device 4 for measuring the power density on the repeater mounted on the satellite station 1 from the received power of the modulated signal from the control station 3 is provided, and when the control station 3 receives the line connection request signal, this power density The measuring device 4 measures the power density on the repeater mounted on the satellite station 1 and determines whether or not a new satellite communication line can be set. That is, the power density measuring device 4 includes, for example, a power density measuring means for measuring the power density on the repeater mounted on the satellite station 1, a measured value by the power density measuring means, and a preset power density. A judgment means for judging whether or not a new satellite communication line can be set by comparing with an allowable value is provided (not shown), and the number of satellite communication lines set via the repeater is set. A function of monitoring the power density on the repeater mounted on the satellite station 1 is added so that the power density of the repeater mounted on the satellite station 1 does not exceed the allowable value.

When the measured value of the power density measured by the power density measuring device 4 is larger than a preset allowable value, a new satellite is provided to avoid the influence of radio wave interference on other satellite communication systems. It is determined that the communication line cannot be set. Further, when the measured value of the power density measured by the power density measuring device 4 is smaller than the preset allowable value, there is a margin in the number of satellite communication lines, and a new satellite communication line can be set. To determine.

Here, the allowable value of the power density to be compared with the measured value of the power density measured by the power density measuring device 4 will be described with reference to FIG. FIG. 4 is a power density characteristic diagram showing the relationship between the power density of the repeater mounted on the satellite station 1 and the allowable value when determining whether or not a new satellite communication line can be set. In FIG. 4, the horizontal axis represents frequency, the vertical axis represents power density, and 18 is a primary-modulated primary-modulated signal before being subjected to spread processing in the modulation / demodulation means 13 of a certain earth station,
Numerals 19 to 21 are spread signals subjected to spread processing using a spread code unique to each earth station. As shown in FIG.
The communication signal 18 primary-modulated by the modulator / demodulator 13 is a signal with a high power density, but when spread processing is performed with a spreading code, it is a spread signal with a low power density with a widened bandwidth as shown by 19 and 20. Become. In a code division multiple access satellite communication system, a communication channel composed of such spread signals is used as a satellite communication line between each earth station, and many satellite communication lines are set using the same frequency. Is possible.

However, in the communication channels using such spread signals, as the number of communication channels increases, the power density of the repeater mounted in the satellite station 1 also gradually increases, and the allowable value for other satellite communication systems is increased. The problem arises of giving more interference. Further, even if the spread signal is subjected to the despreading process at each earth station, the reproduced primary modulation signal is buried in the spread signal, and the original communication signal cannot be reproduced accurately. Therefore, the limit value of the power density at which the above problems occur is set to the allowable value Dt.
The satellite communication line is set so that the measured value of the power density on the repeater measured by the power density measuring device 4 does not exceed the allowable value Dth.

When the control station 3 determines that the power density measuring device 4 cannot set up a new satellite communication line, the common control line 7 limits the setting of the new satellite communication line based on the determination. Earth station 2 originating via
The limit signal is notified to -1. This limiting signal is received by the earth station 2-1 which is the transmission source via the satellite station 1. The earth station 2-1 which is the transmission source of this limited signal
Judges that the satellite communication line cannot be set up, and stops the connection request for the satellite communication line.

Further, when the control station 3 determines that the power density measuring device 4 can set up a new satellite communication line, the common control line allows the setting of a new satellite communication line based on the determination. The permission signal is sent to the source earth station 2-1 and the destination earth station 2-2 via 7. The earth station 2-2, which is the transmission destination, is also notified of the transmission source information together with the permission signal in order to inform which earth station the transmission source is. This permission signal is received by the earth station 2-1 which is the transmission source via the satellite station 1, and the permission signal and the information of the transmission source are received by the earth station 2-2 which is the transmission destination via the satellite station 1. .

Then, the earth station 2-1 and the earth station 2-2, which have received the permission signal from the control station 3, judge that satellite communication with the other party of communication is possible, and perform the spreading process using the spreading code of the own station. The applied communication signal is transmitted via the satellite station 1 to the earth station of the communication partner. Further, in the earth station that has received the spread signal transmitted from the communication partner, the spread code of the communication partner can be known based on the spread code table 17 stored in the spread code table storage unit 15, and the corresponding earth station can be known. It is possible to reproduce the communication signal transmitted from the earth station of the communication partner using the spreading code of. In this way, since the information of the originating earth station is notified to the originating earth station, mutual communication can be realized between these earth stations.

According to the above example, the originating earth station 2
Since the information of -1 is notified to the destination earth station 2-2, the earth station 2-2 reverses the spread signal received using the unique spreading code assigned to the earth station 2-1. By performing the diffusion process, the communication signal transmitted from the earth station 2-1 can be reproduced. The earth station 2-1 which is the transmission source can similarly reproduce the communication signal transmitted from the earth station 2-1 by using the spreading code of the earth station 2-2 which is the transmission destination.

As described above, each of the earth stations 2-1 to 2-n constantly monitors the signal transmitted from the common control line 7, and the earth station 2-1 receives the control station 3 via the common control line 5. When the restriction signal is received from the terminal, it judges that the earth station 2-1 satellite communication line cannot be set and cancels the line connection request.
When the permission signal from the control station 3 is received, the earth station 2
-1 and the earth station 2-2, the setting of the modulation / demodulation means 13 is switched to the satellite communication line to set the satellite communication line, and the transmission and reception of the communication signal is started. For example, Earth Station 2-
When the transmission / reception by the satellite communication line 8 is started, the reference numeral 1 indicates a communication signal which has been spread using the spread code C1 of the own station based on the spread code table 17 stored in the spread code table storage unit 15 of the own station. It transmits via the transmitting / receiving antenna 9. Also, the received signal from the earth station 2-2 received by the transmitting / receiving antenna 9 is subjected to despreading processing using the spread code C2 of the earth station 2-2 to reproduce the original communication signal.

As described above, in the satellite communication system according to the first embodiment, the CDMA system is adopted as the communication channel division system of the satellite communication line, and the satellite station 1
Since the satellite communication line is set according to the power density of the repeater mounted on the satellite, each earth station 2-1 to 2-n
Can set the satellite communication line without receiving the notification of the empty channel from the control station 4. In addition, in each earth station which is the receiving side, the information of the transmitting side earth station notified from the control station 4 Based on the spread code table 17 stored in the spread code table storage unit 15, the spread code used in the transmitting earth station can be recognized, and the spread code used in the transmitting earth station can be used. By performing demodulation processing on the received signal, the information transmitted from the transmitting earth station can be reproduced.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a system schematic diagram schematically showing a satellite communication system according to a second embodiment of the present invention. In FIG. 5, 4b denotes each earth station 2
It is a power density measuring device provided on the -1 to 2-n side. The difference from the satellite communication system according to the first embodiment is that a power density measuring device 4b having the same function as the power density measuring device 4 provided on the control station 3 side is installed in each earth station 2-.
This is a point provided on the side of 1 to 2-n. In the drawings, the same reference numerals indicate the same or corresponding parts, and detailed description thereof will be omitted.

In the satellite communication system according to the second embodiment, a power density measuring device 4b for measuring the power density on the repeater mounted on the satellite station 1 is provided on each of the earth stations 2-1 to 2-n. Therefore, each of the earth stations 2-1 to 2-n can judge whether or not the satellite communication line can be set before transmitting the line connection request signal to the control station 3. By transmitting the line connection request signal only when setting is possible, the common control line can be effectively used as a satellite communication system. In addition, the control station 3 side does not need to determine whether or not the satellite communication line can be set,
The satellite communication between these earth stations can be realized only by notifying the earth station of the transmission destination of the information of the transmission source transmitted together with the line connection request signal.

As described above, also in the satellite communication system according to the second embodiment, the control station 3 can set the satellite communication line without controlling the complicated line allocation. Further, as in the satellite communication system according to the first embodiment, both the transmitting and receiving earth stations can recognize the spreading code of the communicating earth station, so the spreading code used in the communicating earth station. It is possible to realize satellite communication between each earth station by reproducing the original signal using.

[0037]

As described above, according to the present invention, a plurality of earth stations make a connection request for a satellite communication line by the code division multiple access system, and the earth station that has made a connection request for this satellite communication line. As a result of the notification of whether or not the satellite communication lines can be set according to the power density of the repeaters installed in the satellite stations, the satellite communication lines can be used despite the increase in the number of relay lines relayed by the satellite stations. Can be used efficiently, while D
A satellite communication line can be easily set between each earth station without providing an AMA device or the like and controlling the complicated line connection for the line allocation or the like by the DAMA device or the like.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a satellite communication earth station according to the first embodiment of the present invention.

FIG. 3 is a data configuration diagram showing an example of a spreading code table used in the satellite communication earth station shown in FIGS. 1 and 2.

4 is a power density characteristic diagram showing a relationship between a power density of a repeater mounted on the satellite station 1 shown in FIG. 1 and an allowable value when determining whether or not a new satellite communication line can be set.

FIG. 5 is a system schematic diagram schematically showing a satellite communication system according to a second embodiment of the present invention.

[Explanation of symbols]

1 satellite station, 2, 2-1 to 2-n satellite communication earth station (earth station), 3 control station, 4, 4b power density measuring device, 5 terminal device, 7 common control line, 8 satellite communication line (communication channel) ), 9 transmission / reception antennas, 13 modulation / demodulation means, 14 line control means, 15 spreading code table storage section, 16 interface device, 17 spreading code table.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5K022 EE01 EE14 EE21 EE31                 5K072 AA15 BB22 CC20 CC25 DD01                       DD16 DD17 EE03 EE12 FF03                       FF05 GG25

Claims (5)

[Claims] 1. A satellite communication system in which a frequency band of a repeater mounted on a satellite station is divided into a plurality of communication channels by a code division method, and a plurality of earth stations of the plurality of communication channels use it as a satellite communication line. A satellite communication line connection method, wherein when any one of the earth stations requests connection to the communication channel, the power density of a repeater mounted on the satellite station is measured, and the power density is equal to or more than an allowable value. In the case of, the use of the satellite communication line of the earth station that has made the connection request is restricted, and when the power density is smaller than the allowable value, the earth station that has made the connection request and the earth station that is the communication partner thereof. The satellite communication line connection method according to claim 1, wherein the use of the satellite communication line is permitted. 2. A satellite station equipped with a repeater, a plurality of earth stations requesting connection of a satellite communication line by a code division multiple access system via this satellite station, and a common earth station shared by these plurality of earth stations. Measure the power density of the repeater mounted on the satellite station via the control line, and request the connection of the satellite communication line via the satellite station when the measured power density of the repeater is above the allowable value. The earth station was informed of the limit signal for limiting the connection of the satellite communication line, and when the measured power density of the repeater was smaller than the allowable value, the connection of the satellite communication line was requested via the satellite station. An earth station and a control station that notifies the earth station that is a communication partner of the earth station of a permission signal permitting the connection of the satellite communication line;
The plurality of earth stations have a spread code table made up of a plurality of spread codes set for each earth station, and based on this spread code table, transmit a spread signal spread by the spread code of the own station to a communication partner. On the other hand, the satellite communication system is characterized in that the received signal from the communication partner is reproduced by the spread code of the communication partner. 3. A satellite station equipped with a repeater, a plurality of earth stations requesting connection of a satellite communication line by a code division multiple access system via the satellite station, and a plurality of earth stations respectively provided in these earth stations, The power density of the repeater mounted on the satellite station is measured through a common control line shared by these earth stations, and when the measured value is above the allowable value, it is determined that the satellite communication line cannot be connected. However, when the measured value is smaller than the allowable value, a power density determination device that determines that the satellite communication line can be connected, and a connection request for the satellite communication line from the plurality of earth stations are received, and the connection request is accepted. A control station that notifies the earth station that is the other party of the information of the earth station that has been performed, the plurality of earth stations makes a connection request for the satellite communication line according to the determination of the power density determination device, And , A spread signal spread by the spread code of the own station based on a spread code table composed of a plurality of spread codes set for each earth station is transmitted to the communication partner, while a received signal from the communication partner is transmitted to the communication partner. A satellite communication system characterized in that the data is reproduced by the spread code of. 4. The satellite communication system according to claim 2, wherein the earth station stores a spread code table notified from the control station via a satellite station. 5. A satellite communication line connection request by a code division multiple access system is made through a common control line shared by a plurality of satellite communication earth stations, and another earth is made by a satellite communication line set based on this connection request. In a satellite communication earth station that communicates with a station, a radio wave signal is transmitted to another earth station which is a communication partner via the satellite station, and is transmitted from the other earth station which is a communication partner via the satellite station. A transmitting / receiving antenna for receiving a radio wave signal, a receiving unit for receiving and processing a radio wave signal received by the transmitting / receiving antenna, and a spreading code table storing a spreading code table composed of a plurality of spreading codes assigned to each of the plurality of earth stations. Reception processing by the reception unit using a code table storage unit and a spread code of another earth station that is the other party of communication based on the spread code table stored in the storage unit A satellite communication earth station, comprising: demodulation means for performing despreading processing on the received signal thus received to reproduce the original communication signal.