KR20110057029A - Apparatus and method for transmitting data in a terminal of satellite communication system - Google Patents

Abstract

PURPOSE: An apparatus and method for transmitting data in a terminal of a satellite communication system are provided to enhance the efficiency of a transmitter of high power consumption in satellite communication. CONSTITUTION: A baseband signal processing unit(200) modulates data signals into IF(Intermediate Frequency) signals. After amplifying a synthesized signal, the baseband signal processing unit extracts only predetermined band. A transmission signal processing unit(230) extracts phase content and amplification content from the extracted signal. After amplifying divided amplitude content and amplitude-limited phase content, the transmission signal processing unit outputs the synthesized signal as the band signal for satellite transmission.

Description

Apparatus and method for transmitting data from a terminal of a satellite communication system {APPARATUS AND METHOD FOR TRANSMITTING DATA IN A TERMINAL OF SATELLITE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for transmitting data in a terminal of a wireless communication system, and more particularly, to an apparatus and method for transmitting data in a terminal of a satellite communication system.

"The present invention is derived from the research carried out as part of the development project of the Korea Communications Commission and Korea Electronics and Telecommunications Research Institute [Task No. 2009-F-039-01, Title: Development of core technology for high efficiency satellite return link connection] . "

In general, satellite communication is a communication method for relaying signals by satellites that are launched in a certain air space outside the atmosphere. In other words, the communication satellite acts as a microwave repeater floating in the sky.

Satellite communication transmits a radio wave to a communication satellite when transmitting a radio wave from the ground so that a signal can be transmitted to other users on the ground. A communication satellite receives radio waves transmitted from the ground, converts and amplifies frequencies, and transmits them to the ground again. The reason why the frequency transmitted from the ground and the frequency transmitted from the satellite is different is to avoid interference of up and down signals.

The earth station is the place that acts to lift the radio wave toward the satellite and receive the radio wave from the ground that the satellite re-shoots. In actual communication, the sender first sends a signal to the earth station, and the earth station sends the signal to the satellite. The satellite receives the radio wave emitted from the earth station, converts the frequency, amplifies it, and sends it back to the earth station. The earth station sends the signal received from the satellite to the other party, the final destination, so that the sender's signal reaches the receiver.

The types of satellites are classified according to their position. Geostationary Earth Orbit (GEO) at the same orbit (about 36,000 km altitude) on Earth's rotation cycle, Middle Earth Orbit (MEO) at altitudes of 5,000 to 25,000 km, altitude 300 to 1500 km Low Earth Orbits (LEOs) located at, and High Earth Orbits (HEOs) with elliptical periods.

The advantage of satellite communication is that it can use large bandwidth to communicate large capacity, low communication cost and improved line quality. In addition, the use of satellite communication expands the coverage area and enables high-speed transmission using high frequency radio waves. Since satellite communication uses microwaves, high-speed and large-capacity communication is possible, and large areas can be used as communication areas. In addition, normal (even) communication is possible regardless of the terrain, and even if a disaster occurs, communication is not restricted.

In other words, the advantages of satellite communication are broadcasting, wide area, flexibility and speed of circuit setting, and disaster resistance.

Broadcasting means that the same information can be transmitted to multiple recipients at the same time, and wide area means that one satellite can cover about one-third of the earth's surface, allowing communication over a large area. The flexibility and speed of circuit setup means that communication lines can be set up anywhere just by installing the earth station, and the earth station can be easily installed, added, removed, and moved. Disaster resistance means that there are few parts installed on the ground of the satellite communication system, so the impact of the ground disaster is very small.

1 is a structure of a general satellite communication system.

The remote earth station system includes an antenna unit 101, a transceiver (not shown), an orthomode transducer (OMT) 104, a Tx Reject Filter (TRF) 105, and a block up converter (BUC) 107. ), An outdoor unit (Out-Door Unit (ODU)) 100 composed of a Low Noise Block (LNB) 109 and the like, and an indoor unit (In-Door) in the form of a set-top-box (STB). Unit: IDU) 110 is divided into equipment.

The antenna unit 101 of the outdoor unit (ODU) 100 is a device that transmits and receives a communication satellite and a data signal, and is composed of a reflector plate 101 and a feed horn 103 having an arbitrary radius. In addition, the transceiver of the ODU converts the frequency of the L band (Band) to the Ku band (Band) frequency and increases the output power.

In addition, the IDU 110 is composed of a modem and a power supply in the form of a set-top-box.

Such application fields include satellite telephony, telemedicine, and the like, as well as personal mobile communications, aeronautical mobile communications, and maritime communications. It also includes flood control and forecasting, river monitoring, meteorological observations and air quality measurements using remote monitoring and control functions.

In addition, satellite communication is very advantageous for communication between books, wallpaper, and mobile devices, and satellite broadcasting can solve TV blind spots in mountain walls or downtown building areas, and can provide a variety of high-quality services.

Recently, satellite communication has attracted attention as an attractive means of next-generation personal communication services, and among them, communication methods using low or mid-orbit are being actively promoted.

Satellite communication technology requires a terminal structure in the form of a portable terminal for use in disaster / disaster communication networks and military operations. In order to develop a portable terminal for satellite communication, the terminal must operate using a battery, and a technique for reducing power consumption of the terminal is required for a long time operation.

Accordingly, the present invention provides a transmission apparatus and method for data transmission in a terminal of a satellite communication system using a battery.

In addition, there is provided a transmitter apparatus and method capable of long-term communication by increasing the efficiency of the transmitter in a portable satellite communication terminal.

An apparatus according to the present invention is a data transmission apparatus of a satellite communication system, and synthesizes a data signal of in-phase (I) and quadrature (Q) by modulating analog signals into intermediate frequency signals, respectively, and synthesizes the synthesized signals. A base signal processor for amplifying and extracting only a predetermined band, and separating a phase component and an amplifying component from the extracted signal, and up-converting the separated phase component to a band of a frequency band for the satellite communication And a transmission signal processor configured to limit the amplitude, amplify the separated amplitude component and the amplitude limited phase component into a predetermined gain value, and output the combined signal as a signal of a band for transmission to the satellite.

In addition, the method according to the present invention is a method for transmitting data in a satellite communication system, generating a signal for modulating an in-phase (I) signal and a quadrature (Q) signal into a predetermined intermediate frequency band, and generating the signal. And modulate the in-phase signal and the quadrature signal by synthesizing the in-phase signal, synthesizing the modulated in-phase signal and the quadrature signal, respectively, amplifying the synthesized signal to a predetermined gain value, and then only a predetermined band. Extracting a phase component and an amplitude component from the extracted signal, mixing a frequency band signal generated to transmit the separated phase component to a satellite, up-converting the frequency, and limiting it to a preset amplitude, Amplifying the amplitude limited phase component to a predetermined gain value and separating the phase simultaneously with the phase component processing Process for amplifying to a predetermined gain value to extract only the amplitude component, and comprises the step of combining the amplified phase signal and the amplified amplitude signal.

Applying the present invention, there is an advantage that can increase the efficiency of a high power consumption transmitter in satellite communication of the terminal behavior.

The above objects, features, and advantages will be described in detail with reference to the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an apparatus for transmitting data in a terminal of a satellite communication system according to an embodiment of the present invention.

The satellite communication terminal is composed of a base signal processor 200 and a transmission signal processor 230. The base signal processor 200 generates a modulated signal in an intermediate frequency (IF) signal band, and the transmit signal processor 230 has a structure for frequency up-converting the modulated signal into a radio frequency (RF) signal.

The base signal processor 200 may include a modulator 201, a switching power amplifier 222, and a TXF 224.

The modulator 201 may include two digital-to-analog converters 202 and 203, an I / Q modulator 204, and an intermediate frequency generator 208.

When the transmitter is operated, the base signal processor 200 generates an internal modem (not shown) in the digital form of the baseband signal. The modem is generated by separating I (n), which is an in-phase component of baseband digital data, and Q (n), which is a quadrature component. The generated digital baseband signals I (n) and Q (n) are converted to analog baseband signals I (t) and Q (t) through respective digital-to-analog converters (D / A) 202 and 203. Is converted.

The I / Q modulator 204 receives the converted analog baseband signals I (t) and Q (t) and performs phase modulation. I / Q modulator 204 uses two orthogonal signals, I (in-phase) and Q (quadrature), to produce a single complex waveform.

I / Q modulator 204 includes two RF up frequency mixers 205 and 207 to convert each quadrature input signal to an RF carrier frequency. Of the analog baseband signals I (t) and Q (t) converted by the digital-to-analog converters 202 and 203, I (t) is provided to the I-up frequency mixer 205 and Q (t). To the Q-uplink frequency mixer 207.

The intermediate frequency generator 208 includes a phase locked loop (PLL) 212, a local oscillator 214, three amplifiers 209, 210, and 216, and a divider 218. Can be.

Phase locked loop (PLL) 212 is a frequency negative circuit configured to maintain a constant frequency of an output signal at all times, such that the signal is held at a particular phase. In other words, the correct fixed point is forcibly held so that the phase of the periodic signal is not shaken. In particular, the present invention is used to prevent the shaking of the frequency used as a frequency source.

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라 할 수 있다.Local oscillator 214 supplies local oscillation frequencies for frequency synthesis to I-up frequency mixer 205 and Q-up frequency mixer 207. The local oscillator 214 may be configured in two, and the outputs of the two local oscillators have a phase difference of 90 degrees. For example, each output

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The amplifier 216 amplifies a signal having a phase difference of 90 degrees generated by the local oscillator 214, and then divides the amplified signal into two signals, I and Q axes, through the divider 218.

The I-axis local oscillation frequency amplifies the signal through amplifier 209 and multiplies the I-up frequency mixer 205 to upconvert the I-axis signal to an intermediate frequency (IF) frequency. In addition, the Q-axis local oscillation frequency is amplified by the amplifier 210 and multiplied by the Q-uplink mixer 207 to convert it to an intermediate frequency.

The signal synthesizer 220 combines the I (t) and Q (t) signals upconverted to the intermediate frequency into the RF signal carrying the phase signal.

The switching power amplifier 222 amplifies the RF signal summed by the signal synthesizer 220. The switching power amplifier 222 varies the power supply voltage to generate an envelope signal. That is, the power of the transmitting device provided as a bias of the switching power amplifier 222 is used to control the output size of the switching power amplifier 222.

The TXF 224 is a band band filter and receives a signal output from the switching power amplifier 222 and passes only a predetermined channel frequency band. The signal passing through the filter is input to the transmission signal processor 230.

The transmission signal processor 230 is configured to separate the RF signal (a) input from the base signal processor 200 into an amplitude component and a phase component, amplify each of them, and add the amplified components.

The structure of the transmission signal processor 230 according to the present invention uses a polar transmitter conversion scheme to convert the modulation signals I and Q data of the intermediate frequency signal band into amplitude data and phase data.

Looking at the polar transmitter, it is a structure that separates the amplitude (amplitude) and phase signal (phase) from the baseband digital signal, and amplifies and combines through a switching PA.

The transmission signal processor 230 according to the present invention may include an amplitude processor 231, a phase processor 240, and a combiner 260.

The amplitude processor 231 may include an envelope detector 232 and a power amplifier 233. The phase processor 240 includes a phase locked loop (PLL) 242, a local oscillator 244, an amplifier 246, an up frequency mixer 248, a limiter 250, and a power amplifier 252. It can be configured as.

The envelope detector 232 detects only an amplitude component from an RF signal (reference numeral a) input to the transmission signal processor 230, and a waveform passing through the envelope detector 232 is as shown in (b). The power amplifier 233 receives the amplitude signal output from the envelope detector 232 and amplifies the signal to a predetermined gain value.

The phase component in the RF signal (reference code a) input to the transmission signal processor 230 up-converts the frequency of the L band (Band) to the Ku band (Band) frequency through the phase processor 240.

The phase locked loop (PLL) 242 forcibly grasps an accurate fixed point so that the phase of the periodic signal does not shake, thereby keeping the frequency constant at all times. Therefore, in the present invention, it is used to prevent the shaking of the frequency used as the frequency source.

The local oscillator 244 supplies a local oscillation frequency for frequency synthesis to the uplink mixer 248. The amplifier 246 amplifies the signal generated by the local oscillator 244 and then up-converts the frequency of the L band (Band) to the Ku band (Band) frequency by multiplying the up-frequency mixer 248.

The up-converted signal proceeds through the limiter 250 to maintain the signal of phase modulation PM before being supplied to the power amplifier 252. The limiter 250 is used to remove the amplitude component from the modulated signal and input it to the power amplifier 252. The waveform passing through the limiter 250 is the same as (c) and is input to the power amplifier 252 and amplified to a predetermined gain value.

The combiner 260 receives and combines the amplified amplitude signal output from the amplitude processor 231 and the phase signal up-converted to the Ku band frequency through the phase processor 240.

3 is a block diagram of an apparatus for transmitting data in a terminal of a satellite communication system according to another embodiment of the present invention.

The configuration diagram of the base signal processor 200 of the transmitter of FIG. 3 is the same as that of FIG. 2, and the satellite processor 310 of the transmitter signal processor 300 is different. In particular, only the position of the limiter 320 of the phase processor 310 is incorrect. That is, the limiter 250 is positioned after the uplink mixer 248 in FIG. 2, but the limiter 250 is positioned before the uplink mixer 248 in the configuration of FIG. 3.

In FIG. 3, a phase component in an RF signal (reference numeral a) input to the transmission signal processor 300 passes through the limiter 320 to protect a phase modulated signal. Limiter 320 generates a limited transmit signal having a limited amplitude and the same phase as the input phase signal. In order to up-convert the phase signal generated by the limiter 320 to the Ku band frequency, the phase locked loop (PLL) 312 is used to prevent the shaking of the frequency used as the frequency source. The local oscillator 314 supplies a local oscillation frequency for frequency synthesis to the uplink frequency mixer 318. The amplifier 316 amplifies the signal generated by the local oscillator 314 and then up-converts the frequency of the L band (Band) to the Ku band (Band) frequency by multiplying the up frequency mixer 318.

Since the power amplifier 322 amplifies only a signal having a phase component, it is possible to increase the efficiency of the power amplifier 322.

The combiner 260 receives and combines the amplified amplitude signal output from the amplitude processor 231 and the phase signal up-converted to the Ku band frequency through the phase processor 310.

1 is a structure of a general satellite communication system,

2 is a block diagram of a high efficiency transmission apparatus for satellite communication according to an embodiment of the present invention;

3 is a block diagram of a high efficiency transmission apparatus for satellite communication according to another embodiment of the present invention.

Claims (7)

In the data transmission apparatus of the satellite communication system, A base signal processor for synthesizing the in-phase (I) signal and the quadrature (Q) data signal by modulating analog signals into intermediate frequency signals, amplifying the synthesized signal, and extracting only a predetermined band; A phase component and an amplification component are separated from the extracted signal, the separated phase component is up-converted into a band of a frequency band for the satellite communication, and then limited to a predetermined amplitude, and the separated amplitude component and the amplitude limited And a transmission signal processing unit for amplifying a phase component to a predetermined gain value and combining the combined components and outputting the combined signal as a signal of a band for transmission to the satellite. The method of claim 1, wherein the base signal processor, A modulator for generating a signal for modulating the in-phase signal and the quadrature signal into a predetermined intermediate frequency band, synthesizing the generated signal, and modulating the in-phase signal and the quadrature signal; A switching power amplifier for amplifying the modulated signal to a predetermined gain value; And a filter for extracting a signal of a predetermined band of frequency from the amplified signal. The method of claim 2, wherein the modulator, A digital analog converter for converting the in-phase signal and the quadrature signal into an analog signal; A carrier frequency generator for generating two frequencies having a phase difference of 90 degrees at a predetermined frequency; Generating a signal for modulating the analog in-phase signal and the quadrature signal into a predetermined frequency band, and synthesizing the generated carrier frequency signal to modulate the in-phase signal and the quadrature signal; Apparatus for transmitting data in a terminal of a satellite communication system comprising a Q modulator. The method of claim 1, wherein the transmission signal processing unit, An amplitude preprocessor for extracting and amplifying only an amplitude component from the signal output from the base signal processor; A satellite processor for upconverting the separated phase component into a band of the frequency band for the satellite communication and then limiting it to a predetermined amplitude and amplifying the amplitude limited phase component to a predetermined gain value; And a combiner for combining the amplified amplitude signal and the amplified phase signal. The method of claim 4, wherein the amplitude preprocessor, An envelope detector for extracting only an amplitude component from a signal output from the base signal processor; And an amplifier for amplifying to a predetermined gain value. The method of claim 4, wherein the phase processing unit, A mixer for mixing a signal of a phase component output from the base signal processor and a signal of a frequency band generated for transmission to a satellite and upconverting the frequency; A limiter for limiting the output of the frequency up-converted phase signal to a preset amplitude; And an amplifier for amplifying the amplified limited phase signal to a predetermined gain value. In a method for transmitting data in a satellite communication system, Generating a signal for modulating an in-phase (I) signal and a quadrature (Q) signal into a predetermined intermediate frequency band, combining with the generated signal to modulate the in-phase signal and the quadrature signal, and respectively Synthesizing the modulated in-phase signal and the quadrature signal, amplifying the synthesized signal to a predetermined gain value, and extracting only a predetermined band; A phase component and an amplification component are separated from the extracted signal, and a signal of a frequency band generated for transmitting the separated phase component to a satellite is mixed up and frequency-converted, and then limited to a preset amplitude. Amplifying to a predetermined gain value, Simultaneously extracting only the separated amplitude components and amplifying them to a predetermined gain value simultaneously with the phase component processing; And combining the amplified amplitude signal with the amplified phase signal.

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