JP3545217B2 - Earth station equipment for FDMA satellite communication - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a through repeater satellite communication system that performs communication by a frequency division multiple access system (FDMA) in which a frequency band allocated to a system is divided and used in a plurality of channels, and does not perform signal processing on a satellite. The present invention relates to an earth station apparatus, and more particularly to an earth station apparatus for FDMA satellite communication that employs a channel allocation method capable of frequency allocation capable of effectively utilizing frequencies by reducing adjacent channel interference.
[0002]
[Prior art]
In a frequency division multiple access system (FDMA) in which a frequency band is divided into a plurality of channels and used in a plurality of channels, in order to effectively use a frequency band allocated to a system, a small frequency interval is set within a usable frequency band. It should just be arranged in. However, if the interval between adjacent channels is smaller than the occupied bandwidth of each channel, the frequency components of the adjacent channels overlap each other, causing adjacent channel interference and deteriorating the line quality.
[0003]
Therefore, conventionally, channels are arranged in consideration of adjacent channel interference. FIG. 7 shows the relationship between the occupied bandwidth of the channel and the interval between adjacent channels. In the figure, (a) shows a case where the occupied bandwidth is equal to the adjacent channel interval. Since the frequency of the desired channel and the frequency of the adjacent channel do not overlap, adjacent channel interference does not occur, but the interval between adjacent channels increases.
[0004]
(B) is a case where the interval between adjacent channels is smaller than the occupied bandwidth. Since the frequency of the desired channel and the frequency of the adjacent channel overlap, adjacent channel interference occurs. Therefore, it is necessary to set the adjacent channel interval so that the amount thereof becomes equal to or less than the allowable interference amount of the system.
[0005]
(C) is a case where the interval between adjacent channels is smaller than (b). Since the overlap between the frequency of the desired channel and the frequency of the adjacent channel becomes large, adjacent channel interference larger than the allowable interference amount of the system occurs. Therefore, the system cannot be established with such a channel arrangement.
[0006]
[Problems to be solved by the invention]
As described above, in a frequency division multiple access (FDMA) communication system in which a frequency band is divided into bands and used by a plurality of channels, the distance between adjacent channels is conventionally limited by adjacent channel interference, and the amount of the adjacent channel is limited by the system. Since it is necessary not to exceed the amount of interference, there has been a problem that the effective use of the frequency must be limited.
[0007]
The present invention relates to a through repeater satellite communication system that uses a frequency division multiple access system (FDMA) that divides a frequency band allocated to a system and uses the frequency band for a plurality of channels, and that does not perform signal processing on a satellite. It is an object of the present invention to provide a method of allocating a frequency to each channel, which can reduce adjacent channel interference and effectively use a frequency.
[0008]
[Means for Solving the Problems]
According to the invention, the above-mentioned problem is solved by the means as set forth in the claims. That is, the invention of claim 1 uses a frequency division multiple access system in which a frequency band is divided into bands and used by a plurality of channels, and a satellite repeater earth communication system of a through repeater in which a satellite amplifies and transmits a received wave. And
[0009]
Means for arranging the transmission channel of the own station adjacent to the reception channel and arranging the transmission channel of the own station so as to allow the frequency band of the adjacent reception channel to overlap, and modulation means for modulating a signal to be transmitted. Transmitting means for transmitting a transmission signal modulated by the modulation means to a satellite, receiving means for receiving a reception signal from the satellite,
[0010]
Phase conversion means having a function of converting the phase of the transmission signal modulated by the modulation means to an opposite phase, and inserting a signal delay time until the transmission signal is received back to the earth station via a satellite; A synthesizing unit for synthesizing a reception signal received by the receiving unit and a transmission signal of the own station converted by the phase conversion unit, and a demodulation unit for demodulating a signal output by the synthesizing unit. This is an earth station device for FDMA satellite communication.
[0011]
According to a second aspect of the present invention, in the earth station device for FDMA satellite communication according to the first aspect, the transmission channel of the own station is adjacent to the reception channel, the occupied bandwidth of the channel is W (Hz), When the interval between a transmission channel and an adjacent reception channel to be received by the own station is Da (Hz), and the interval between the transmission channel of the own station and an adjacent channel that is not a channel to be received by the own station is Db (Hz). , W> Da = Db.
[0012]
According to a third aspect of the present invention, in the earth station device for FDMA satellite communication according to the first aspect, the transmission channel of the own station is adjacent to the reception channel, and the occupied bandwidth of the channel is W (Hz). When a channel interval between a transmission channel and an adjacent reception channel to be received by the own station is Da (Hz) and an interval between adjacent channels that are not channels to be received by the own station is Db (Hz), Db ≧ W> The channel is arranged so as to be Da.
[0013]
According to a fourth aspect of the present invention, in the earth station apparatus for FDMA satellite communication according to the first aspect, the transmission channel of the own station is adjacent to the reception channel, and the occupied bandwidth of the channel is W (Hz). The adjacent channel interval between the transmission channel and the reception channel of the station is set to Da (Hz), the adjacent channel interval which is not the channel to be received by the earth station is set to Db (Hz), and the channels are arranged so that W>Db> Da. It is configured so that
[0014]
As described above, the present invention uses a frequency division multiple access system (FDMA) in which a frequency band allocated to a system is divided into bands and used by a plurality of channels, and does not perform signal processing on a satellite. In the communication system, the own station transmission channel of the same earth station is adjacent to a channel to be received from another station, and the channels are arranged so as to allow overlapping of the frequency band between the adjacent channels.
[0015]
The most important feature of the earth station is to remove interference components from the transmission channel signal of the local station in the reception channel signal and reduce adjacent channel interference. FIG. 1 is a diagram for explaining the principle of an adjacent channel interference removal method according to the present invention. In the figure,
(A) shows an example of channel arrangement in the present invention. In the present invention, the transmission channel and the reception channel of the same earth station are adjacent to each other, and the channels are arranged so that the frequency band between the adjacent channels partially overlaps.
[0016]
(B) is a method of removing received wave and adjacent channel interference. In the received wave of the earth station, the frequency bands of the adjacent own station transmission channel and the own station reception channel partially overlap, so that adjacent channel interference from the own station transmission channel occurs in the reception channel. In order to remove this interference, the received signal is combined with the same signal as the signal of the own station transmission channel in the opposite phase.
[0017]
(C) shows the received signal after interference cancellation. Since the signal of the own station transmission channel is canceled by the combined signal of the opposite phase, adjacent channel interference can be removed as shown in the figure.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 shows a channel arrangement in the first example of the embodiment of the present invention. A transmission channel and a reception channel of the same earth station are made adjacent to each other within a frequency band of a frequency division multiple access system (FDMA), an interval between adjacent channels is smaller than an occupied bandwidth of a channel signal, and the same frequency band between adjacent channels overlaps. Place the channel in.
[0019]
FIG. 3 shows an outline of the configuration of a satellite communication earth station apparatus which enables the frequency allocation according to the present invention by removing interference from a transmission channel signal of the own station to a reception channel signal and reducing adjacent channel interference. Is shown as a block diagram.
[0020]
In FIG. 3, reference numeral 10 denotes an earth station. In the earth station 10, a modulator 11 for modulating input data, a transmission channel signal received from the modulator 11 is amplified, and another A transmitter 12 for transmitting to an earth station (not shown), a phase shifter 13 for rewriting the phase of a transmission channel signal received from the modulator 11,
[0021]
A receiver 14 for amplifying and outputting a received wave input from another earth station (not shown) via the satellite 20, and a received wave input from the receiver 14 and an opposite phase input from the phase shifter 13 And a demodulation unit 16 for receiving the output from the synthesis unit 15 and demodulating a desired reception channel.
[0022]
Reference numeral 20 denotes a satellite, which amplifies and transmits a received wave. Hereinafter, the operation of the earth station device for FDMA satellite communication will be described with reference to FIG. In FIG. 3, the signal of the own station transmission channel modulated by the modulation unit 11 is transmitted to the satellite 20 via the transmission unit 12, and is also input to the phase shift unit 13, where the phase of the input signal is Is inverted to the opposite phase, a satellite delay time calculated in advance is added, and the result is output to the synthesizing unit 15.
[0023]
The own-station transmission signal is frequency-multiplexed with other channel signals in space, amplified by a satellite, transmitted to the earth station 20, and received by the receiver 14. The reception wave in a state where the occupied band of the own-station transmission channel signal and the desired reception channel signal input to the reception unit 14 overlaps and adjacent channel interference occurs is input to the synthesis unit 15.
[0024]
The combining unit 15 combines the own-station transmission channel signal included in the received wave and the opposite-phase own-station channel signal input from the phase shift unit 13, and cancels and removes the own-station channel signal component. The reception wave from which the own-station transmission component has been removed is input to the demodulation unit 16, and the reception channel signal is demodulated with adjacent channel interference from the own-station transmission channel signal removed.
[0025]
The earth station apparatus for FDMA satellite communication of the present invention can suppress the transmission wave of its own station from interfering with the reception channel by the above operation. Thus, the frequency bands can be arranged so that a part of the frequency bands overlaps, and the frequency band for the channel allocated to the system can be used efficiently.
[0026]
FIGS. 4A and 4B are diagrams showing a channel arrangement according to a second example of the embodiment of the present invention, wherein FIG. 4A shows the channel arrangement, and FIG. 4B shows the reception channel after interference cancellation. In this example, the transmission channel and the reception channel of the same earth station are made adjacent to each other within a frequency band of a frequency division multiple access system (FDMA),
[0027]
The occupied bandwidth of the channel is W (Hz), the adjacent channel interval between the local transmission channel and the channel to be received for the same earth station is Da (Hz), and the adjacent channel interval which is not the channel to be received is Db (Hz). , The channels are arranged such that W> Da = Db.
[0028]
Since the interference from the transmission channel signal of the own station to the reception channel signal is removed in the same manner as in the case of the first embodiment of the present invention described above, the channel is set to a part of its frequency band. Can be arranged to overlap, so that the frequency band for the channel allocated to the system can be used efficiently.
[0029]
FIGS. 5A and 5B are diagrams showing a channel arrangement according to a third example of the embodiment of the present invention. FIG. 5A shows the channel arrangement, and FIG. 5B shows the reception channel after interference cancellation. In this example, the transmission channel and the reception channel of the same earth station are made adjacent to each other within a frequency band of a frequency division multiple access system (FDMA),
[0030]
The occupied bandwidth of the channel is W (Hz), the adjacent channel interval between the local transmission channel and the channel to be received for the same earth station is Da (Hz), and the adjacent channel interval which is not the channel to be received is Db (Hz). , The channels are arranged so that Db ≧ W> Da.
[0031]
Since the interference from the transmission channel signal of the own station to the reception channel signal is removed in the same manner as in the case of the first embodiment of the present invention described above, the channel is set to a part of its frequency band. Can be arranged to overlap, so that the frequency band for the channel allocated to the system can be used efficiently.
[0032]
FIGS. 6A and 6B are diagrams showing a channel arrangement according to a fourth example of the embodiment of the present invention, wherein FIG. 6A shows the channel arrangement, and FIG. 6B shows the reception channel after interference cancellation. In this example, the transmission channel and the reception channel of the same earth station are made adjacent to each other within a frequency band of a frequency division multiple access system (FDMA),
[0033]
The occupied bandwidth of the channel is W (Hz), the adjacent channel interval between the local transmission channel and the channel to be received for the same earth station is Da (Hz), and the adjacent channel interval which is not the channel to be received is Db (Hz). , The channels are arranged such that W>Db> Da.
[0034]
Since the interference from the transmission channel signal of the own station to the reception channel signal is removed in the same manner as in the case of the first embodiment of the present invention described above, the channel is set to a part of its frequency band. Can be arranged to overlap, so that the frequency band for the channel allocated to the system can be used efficiently.
[0035]
【The invention's effect】
As described above, according to the present invention, an earth station of a through repeater satellite communication system that does not perform signal processing on a satellite by using a frequency division multiple access system in which a frequency band is divided into bands and used by a plurality of channels. In the device, it is possible to reduce adjacent channel interference and reduce the interval between adjacent channels, so that more channels can be arranged within the frequency band given to the system, and effective use of frequency can be achieved. There are advantages that can be done.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the principle of an adjacent channel interference removal method according to the present invention.
FIG. 2 is a diagram showing a channel arrangement of a first example of an embodiment of the present invention.
FIG. 3 is a block diagram schematically showing the configuration of the earth station device for satellite communication of the present invention.
FIG. 4 is a diagram illustrating a channel arrangement according to a second example of the embodiment of the present invention;
FIG. 5 is a diagram showing a channel arrangement of a third example of the embodiment of the present invention.
FIG. 6 is a diagram illustrating a channel arrangement according to a fourth example of the embodiment of the present invention.
FIG. 7 is a diagram illustrating a relationship between an occupied bandwidth of a channel and an interval between adjacent channels.
[Explanation of symbols]
Reference Signs List 10 earth station 11 modulator 12 transmitter 13 phase shifter 14 receiver 15 synthesizer 16 demodulator 20 satellite

Claims (4)

An earth station apparatus for a through repeater satellite communication system in which a frequency band is divided into bands and a frequency division multiple access method is used in a plurality of channels, and a satellite amplifies and transmits a received wave .
Means for arranging the transmission channel of the own station adjacent to the reception channel and allowing the frequency band of the transmission channel of the own station to overlap with the frequency band of the adjacent reception channel;
Modulating means for modulating a signal to be transmitted;
Transmitting means for transmitting a transmission signal modulated by the modulation means to a satellite,
Receiving means for receiving a received signal from the satellite,
Phase conversion means for converting the phase of the transmission signal modulated by the modulation means to an opposite phase, and inserting a signal delay time until the transmission signal is received back to the earth station via a satellite; ,
Combining means for combining the received signal received by the receiving means and the transmission signal of the own station converted by the phase converting means,
An earth station apparatus for FDMA satellite communication, comprising: demodulation means for demodulating a signal output by the combining means. The transmission channel of the own station is adjacent to the reception channel, the occupied bandwidth of the channel is W (Hz), the interval between the transmission channel of the own station and the adjacent reception channel to be received by the own station is Da (Hz), When an interval between a transmission channel of the own station and an adjacent channel which is not a channel to be received by the own station is Db (Hz),
The earth station apparatus for FDMA satellite communication according to claim 1, wherein the channels are arranged so that W> Da = Db. The transmitting channel of the own station is adjacent to the receiving channel, the occupied bandwidth of the channel is W (Hz), and the channel interval between the transmitting channel of the own station and the adjacent receiving channel to be received by the own station is Da (Hz). 2. The earth station apparatus for FDMA satellite communication according to claim 1, wherein when an interval between adjacent channels which are not channels to be received by the own station is Db (Hz), channels are arranged so that Db ≧ W> Da. . The transmission channel of the own station is adjacent to the reception channel, the occupied bandwidth of the channel is W (Hz), the adjacent channel interval between the transmission channel and the reception channel of the same earth station is Da (Hz), 2. The earth station device for FDMA satellite communication according to claim 1, wherein an interval between adjacent channels that is not a channel to be received is Db (Hz), and channels are arranged so that W> Db> Da.

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