KR100546801B1 - Apparatus and method for demodulation using detection of channel adaptive modulation scheme - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a demodulation device and a method using channel adaptive modulation detection.

2. The technical problem to be solved by the invention

According to the present invention, a modulation scheme is detected directly from a demodulated signal using a modulation scheme detection means without having to transmit the modulation scheme information of the transmitter side to the receiver side and having a plurality of demodulation means assuming all modulation schemes at the receiver side. Accordingly, a demodulation device and a method using channel adaptive modulation scheme detection, which can obtain received data corresponding to adaptive modulation according to a state of a transmission channel by one demodulation means, are provided.

3. Summary of Solution to Invention

The present invention provides a demodulation device using channel adaptive modulation scheme detection, comprising: receiving means for receiving a signal modulated by a channel adaptive modulation scheme from the outside; Demodulation means for demodulating a modulated signal from said receiving means in accordance with modulation scheme information; Modulation scheme detection means for detecting mapping information from the signal demodulated by the demodulation means to determine modulation scheme information and outputting the modulation scheme information to the demodulation means; And decoding means for error correcting and decoding the demodulated signal from the demodulation means using the modulation scheme information from the modulation scheme detection means.

4. Important uses of the invention

The present invention is used in channel adaptive modulation and demodulation communication system.

Adaptive Adaptive Demodulation, Modulation Detection, Demodulation Device, BPSK, QPSK, 8PSK, MPSK

Description

Apparatus and method for demodulation using detection of channel adaptive modulation scheme             

1 is a block diagram of an embodiment of a conventional modulation scheme adaptive transmission device and demodulation device.

2 is a block diagram of an embodiment of a conventional simultaneous multiple adaptive demodulation device.

3 is a block diagram of an embodiment of a demodulation device using channel adaptive modulation detection according to the present invention;

4 is a detailed configuration diagram of an embodiment of the modulation method detection unit of FIG.

5 is an exemplary state transition diagram for a channel adaptive modulation detection method according to the present invention.

6 is a view showing a modulation detection waveform according to the modulation method change in accordance with the present invention.

* Explanation of symbols for the main parts of the drawings

301: antenna 302: high frequency receiver

303: demodulation unit 304: modulation method detection unit

305: decryption unit

The present invention relates to a demodulation device using channel adaptive modulation scheme detection and a method thereof, and more particularly to a plurality of demodulation means assuming all modulation schemes at the receiving side without transmitting the modulation scheme information of the transmitting side to the receiving side. It is not necessary to provide a modulation method directly from the demodulation signal by using the modulation method detection means, by means of a single demodulation means that the received data corresponding to the adaptive modulation according to the state of the transmission channel, channel adaptive modulation The present invention relates to a demodulation device using method detection and a method thereof.

In a wireless communication system, the state of a transmission channel is variable, so that the performance of the transmission signal is flexible. In particular, in the case of satellite communication, attenuation due to rainfall may occur seriously due to the limitation of radio resources and the use of a high frequency band for broadband communication. Therefore, adaptively determine the digits of the modulation according to the quality state of the channel.

For example, if the quality of the channel is good, the multiplier number is increased, and if the channel condition is bad, the multiplier number is reduced to maintain the transmission quality. However, in the receiver, without accurate information on the modulation scheme, even if the quality of the received signal is high, data demodulation is impossible. Therefore, modulation scheme information is essential in a receiver of a communication system to which an adaptive modulation technique is applied.

In the conventional wireless communication system, even if the modulation and error correction coding schemes are fixed and transmitted without considering the channel environment, or the modulation and coding schemes are adaptively transmitted to the channel state, the modulation scheme information has to be transmitted to the receiver. There was this complicated and inefficient problem.

1 is a block diagram of an embodiment of a conventional modulation scheme adaptive transmission device and demodulation device.

As shown in FIG. 1, the frame 101 of the conventional modulation scheme transmission adaptive modulation apparatus is periodically inserted in front of the transmission data 102 and transmitted to the receiving side.

The modulation scheme information 103 should be transmitted in a binary phase shift keying (BPSK) scheme with high quality.

In addition, as shown in FIG. 1, a conventional demodulation device includes a high frequency receiver 111 for processing a radio signal received from an antenna 110, a multi-digit signal based on modulation scheme information, and a code rate signal. A data demodulation unit 113 and a data demodulation unit 113 for demodulating a modulation scheme transmitted from a transmission unit by receiving a polynomial signal from a modulation method detection demodulation unit 112 and the modulation method detection demodulation unit 112. And a decoder 114 for receiving demodulated data and decoding the demodulated data according to a code rate signal received from the modulation scheme detection demodulator 112.

As described above, the conventional modulation scheme adaptive modulation device and demodulation device has a low bandwidth efficiency because the modulation scheme information must be periodically inserted into the transmission data, dedicated modulation to ensure high transmission quality for the modulation scheme information There is a problem that the transmission system is complicated because it must be equipped with a device.

2 is a block diagram of an embodiment of a conventional simultaneous multiple adaptive demodulation device.

As shown in FIG. 2, the conventional simultaneous multiple adaptive demodulation device includes a high frequency receiver 22 for processing a radio frequency received from an antenna 21 and a radio signal processed by the high frequency receiver 22 at a transmitter. Multiple demodulators 231 through 233 for demodulating by the number N of possible modulation schemes, Multiple decoders 241 for correspondingly decoding one-to-one demodulated signals by the multiple demodulators 231 through 233 243 to 243, a plurality of error detectors for detecting an error-free data path in a one-to-one correspondence with respect to the data restored by the plurality of demodulators 231 to 233 and the plurality of decoders 241 to 243 ( And a data selector 26 for receiving a plurality of data and selection signals from the plurality of error detectors 251 to 253 and selecting received data without errors.

Accordingly, the conventional simultaneous multiple adaptive demodulation device has the advantage that no separate device is required at the transmitter and there is no increase in bandwidth, but a plurality of demodulators 231 to 233 for all modulation schemes and coding schemes, and a plurality of decoders. Since the units 241 to 243 and the plurality of error detection units 251 to 253 must be provided, there is a problem in that the complexity of the system is increased.

Meanwhile, a method of transmitting information on a modulation method of a transmitter to a receiver by another transmission channel is also considered. This method has an advantage that there is no increase in bandwidth due to transmission of modulation information and the complexity of the system is not high. However, there is a problem in that data loss occurs due to information transmission delay, and an additional transport channel is required.

The present invention has been proposed to solve the above problems, and does not transmit the modulation scheme information of the transmitting side to the receiving side, and the receiving side does not need to include a plurality of demodulation means assuming all modulation schemes. A demodulation device using a channel adaptive modulation scheme detection, by detecting a modulation scheme directly from a demodulation signal by using a detection means, so as to obtain received data in response to the adaptive modulation according to the state of a transmission channel with one demodulation means; The purpose is to provide a method.

An apparatus of the present invention for achieving the above object comprises: a demodulation device using channel adaptive modulation scheme detection, comprising: receiving means for receiving a signal modulated by a channel adaptive modulation scheme from the outside; Demodulation means for demodulating a modulated signal from said receiving means in accordance with modulation scheme information; Modulation scheme detection means for detecting mapping information from the signal demodulated by the demodulation means to determine modulation scheme information and outputting the modulation scheme information to the demodulation means; And decoding means for error correcting and decoding the demodulated signal from the demodulation means using the modulation method information from the modulation method detection means.

On the other hand, the method of the present invention, a demodulation method using a channel adaptive modulation scheme detection, comprising: a receiving step of receiving a signal modulated by the channel adaptive modulation scheme; Demodulating the received modulated signal according to modulation scheme information; A modulation scheme detection step of detecting mapping information from the demodulated signal to determine and feedback modulation scheme information; And a decoding step of error correcting and decoding the demodulated demodulated signal using the determined modulation scheme information.

In digital modulation, a signal is transmitted by changing one or a combination of phase, amplitude, and frequency of a carrier wave into digital data of 0 and 1. Transmitting a signal by matching a sign to a phase change is called phase shift keying (PSK).

Binary phase shift keying (BPSK) is a basic phase shift keying scheme in which a digital signal having two values (0 or 1) to be transmitted is transmitted in correspondence with two phases of a carrier (ie, zero phase and π phase). Referred to as 'BPSK'.

Unlike BPSK, two bits of digital signals 0 and 1 of two values are collected and transmitted in correspondence with the four phases of the carrier and are referred to as quadrature PSK (QPSK). That is, it transmits by correlating (0, 0) with 0 phase, (0, 1) with π / 2 phase, (1, 0) with π phase, and (1, 1) with 3π / 2 phase. Binary phase shift keying (BPSK) is also referred to as two-phase shift keying and quadrature phase shift keying (QPSK) is also referred to as four-phase shift keying. QPSK modulated waves can transmit twice as much information as BPSK modulated waves in the same frequency band, and are widely used in the voice signal transmission and satellite communication fields of satellite broadcasting.

On the other hand, there are 8 phase shift key modulation (8PSK, hereinafter referred to as '8PSK') that can transmit 3 times the information in the same frequency band, and 16 phase shift modulation (16PSK) that can transmit 4 times the information.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of an embodiment of a demodulation device using channel adaptive modulation detection according to the present invention.

As shown in FIG. 3, the demodulation device using the channel adaptive modulation scheme detection according to the present invention includes a high frequency receiver 302 for receiving a signal modulated by the channel adaptive modulation scheme from the antenna 301. The demodulation signal z (k) demodulated by the modulation unit 303 and the determination signal d (k) determined from the demodulation signal z (k) are inputted to determine modulation scheme information according to mapping detection information. A modulation method detector 304 for outputting the modulation method information to the demodulator 303 and the decoder 305, from the high frequency receiver 302 according to the modulation method information received from the modulation method detector 304; The demodulated signal z (k) is demodulated by outputting the demodulated signal z (k) to the modulation method detector 304 and the decoder 305, and the decision signal d (k) determined from the demodulated signal z (k). Demodulator 303 and the demodulator for outputting the < RTI ID = 0.0 > The decoding unit 305 for error correction and decoding of data using the modulation method information received from the modulation method detector 304 from the second demodulation signal z (k) received from the unit 303. It includes. Detailed configuration and operation of each component will be described below with reference to FIGS. 4 to 6.

4 is a detailed block diagram of an embodiment of the modulation method detection unit of FIG.

As shown in FIG. 4, the modulation method detection unit 304 receives the determination signal from the demodulation unit 303, and the mapping detector 401 at the 8PSK constellation point for detecting the mapping signal at the 8PSK constellation point. The mapping detector 402 receives a determination signal from the grandfather 303 to detect the mapping signal at the QPSK constellation point, and receives a determination signal from the demodulator 303 at the QPSK constellation point to detect the mapping signal at the BPSK constellation point. A QPSK mapping signal is received from the mapping detector 403 at the BPSK constellation point, the QPSK mapping signal from the mapping detector 401 at the 8PSK constellation point, and the QPSK mapping signal from the mapping detector 402 at the QPSK constellation point. A first logical sum operator 404 for selecting, the BPSK mapping signal from the mapping detector 401 at the 8PSK constellation and the BPSK mapping signal from the mapping detector 402 at the QPSK constellation and the BPSK constellation at every A second OR operation 405 for receiving a BPSK mapping signal from the detector 403 and selecting a BPSK modulation scheme, and a demodulation signal z (k) and a determination signal d (k) from the demodulator 303. To detect the demodulation status information The demodulation state detector 406 and the mapping signal detected by the mapping detector 401 at the 8PSK constellation point, the selection signal from the first and second logical sum operators 404 and 405, and the demodulation state detected by the demodulation state detector 406. And a modulation scheme determiner 407 for receiving the state information and determining a modulation scheme.

Table 1 below shows modulation methods that can be demodulated in each demodulator.

The basic concept of the modulation method detection unit 304 is due to the fact that in the MPSK demodulator, all signals modulated by a modulation method lower than M can be demodulated, but a signal modulated by a modulation method higher than M can not be demodulated. .

That is, as shown in [Table 1], the 8PSK demodulator can demodulate all BPSK, QPSK and 8PSK modulation schemes, the QPSK demodulator can demodulate the BPSK and QPSK modulation schemes, and the BPSK demodulator can only demodulate the BPSK modulation schemes. It can be demodulated.

At the plurality of constellation points, the mapping detectors 401 to 403 accumulate constellation points for a predetermined time from the two-dimensional determination symbol signal d (k) received from the demodulator 303 to obtain constellation position information.

In the 8PSK constellation point, the mapping detector 401 may have eight constellation points in an 8PSK demodulation state, assuming the eight constellation points, the decision boundary is determined and the current constellation of the decision signal d (k). Point positions are detected within the crystal boundary and accumulated during t3 symbols. Then, at the 8PSK constellation point, the mapping detector 401 detects a modulation scheme using the position of the constellation point in which the decision signal d (k) received from the demodulator 303 is accumulated for t3 symbols.

That is, if the accumulated constellation point is counted and the threshold value is still detected, the corresponding modulation scheme is locked (locked). If the threshold value is detected below the threshold, the modulation scheme is changed or the modulation scheme detection is failed (unlocked). Therefore, when the positions of the accumulated constellation points above the threshold are arranged at all positions of the eight 8PSK constellation points, in the 8PSK modulation mode, and when the positions of the four QPSK constellation points are placed in the QPSK modulation mode, two BPSK constellation points are positioned. When arranged in the BPSK modulation mode, the modulation information is provided to the modulation scheme determiner 407 so that the modulation scheme determiner 407 selects an appropriate demodulation scheme.

At the QPSK constellation point, the mapping detector 402 may have four constellation points in the QPSK demodulation state, assuming the four constellation positions to determine a decision boundary, and a phenomenon of the received symbol d (k). The degree position is detected within the crystal boundary and accumulated during t2 symbols. Then, at the QPSK constellation point, the mapping detector 402 detects a modulation scheme by using the position of the constellation point in which the decision signal d (k) received from the demodulator 303 is accumulated for t2 symbols.

That is, if the accumulated constellation point is counted and the threshold value is still detected, the modulation method is detected as a lock (lock), and if it is detected below the threshold value, the modulation method is changed or the modulation method detection is failed (unlock). . Therefore, when the positions of the constellation points accumulated above the threshold value are arranged in all four positions, the modulation information is detected by the modulation scheme determiner 407 by detecting in the QPSK modulation mode and in the BPSK modulation mode when disposed at the two BPSK constellation points. The modulation scheme determiner 407 selects an appropriate demodulation scheme.

At the BPSK constellation point, the mapping detector 403 may have two constellation points in the BPSK demodulation state, assuming the two constellation positions, determining a decision boundary and presenting the received symbol d (k). The degree position is detected within the crystal boundary and accumulated during the t1 symbol. Then, at the BPSK constellation point, the mapping detector 403 detects a modulation scheme using the position of the constellation point in which the decision signal d (k) received from the demodulator 303 is accumulated for t1 symbols.

In other words, if the accumulated constellation point is counted and the threshold value is continuously detected, the modulation method is locked (locked). If the threshold value is detected below the threshold value, the modulation method is changed or the modulation method detection is failed (unlocked). Accordingly, when the constellation points accumulated above the threshold value exist, the modulation information is determined in the BPSK modulation mode and provided to the modulation scheme determiner 407 so that the modulation scheme determiner 407 selects an appropriate demodulation scheme.

On the other hand, when the modulation scheme is changed in the transmitter, the receiver loses carrier synchronization and the noise power becomes high. Therefore, the modulation scheme determiner 407 should track the modulation scheme at the transmitter from the signal received at the receiver. In this process, the demodulation state detector 406 checks the noise power caused by the modulation scheme change to obtain the demodulation state information. Detect. The demodulation state information from the demodulation state detector 406 is used for confirming the modulation method selection, thereby increasing the stability of the modulation method determiner 407.

The modulation method determiner 407 determines the modulation method by receiving the mapping information from the mapping detectors 401 to 403 and the demodulation state information detected by the demodulation state detector 406 at the plurality of constellation points.

At the 8PSK constellation point, the mapping detector 401 may detect all modulation schemes received by 8PSK, QPSK, and BPSK. However, at the QPSK constellation point, the mapping detector 402 can detect only the modulation schemes received by the QPSK and BPSK, and the mapping detector 403 at the BPSK constellation point can detect only the modulation schemes received by the BPSK. Therefore, the modulation scheme is determined using the modulation scheme information detected in the constellation point state of each modulation scheme.

8PSK modulation detection is only possible by the mapping detector 401 at the 8PSK constellation point. However, the QPSK modulation method detection information determines the QPSK modulation method detection information qpsk_det as shown in Equation 1 below from the outputs of the mapping detectors 401 and 402 at 8PSK and QPSK constellation points. Here, the QPSK modulation method detection information (qpsk_det) is the QPSK state detection information (qpsk ₈ ) by the 8PSK demodulator or the QPSK state detection information (qpsk) by the QPSK demodulator while the lock state by the demodulation state detector 406 is maintained. _q ), it is determined that the QPSK modulation scheme has been detected.

The BPSK modulation scheme detection information determines the BPSK modulation scheme detection information (bpsk_det) as shown in Equation 2 below from the outputs of the mapping detectors 401 to 403 at the plurality of constellation points. Here, the BPSK modulation method detection information (bpsk_det) is the BPSK state detection information (bpsk ₈ ) by the 8PSK demodulator or the BPSK state detection information (bpsk) by the QPSK demodulator while the lock state by the demodulation state detector 406 is maintained. _q ) or the BPSK modulation method is detected based on the BPSK state detection information (bpsk _b ) by the BPSK demodulator.

5 is a state transition diagram of an embodiment of a channel adaptive modulation detection method according to the present invention.

5 illustrates a state transition process for the modulation method determination process in the modulation method determiner 407 of FIG.

In the 8PSK demodulation detection state 501, both BPSK, QPSK, and 8PSK modulation methods can be detected, and demodulation is selected (501 to 503) according to the detected modulation method to demodulate and then the modulation method is determined (504 to 503). 506), increase the reliability of the modulation scheme decision. On the other hand, if demodulation is impossible (unlock), it informs that demodulation has failed (507).

In the QPSK demodulation detection state 502, BPSK and QPSK modulation methods can be detected, demodulation is selected according to the detected modulation method (502, 503), demodulated, and the modulation method is determined (505, 506). If demodulation is not possible (unlock), modulation scheme detection 501 is selected from 8PSK demodulation capable of detecting all modulation schemes.

In the BPSK demodulation detection state (503), only the BPSK modulation method can be demodulated.BPSK demodulation is selected according to the detected modulation method (503), and then the modulation method is determined (506). unlock) selects a modulation scheme detection 501 in 8PSK demodulation capable of detecting all modulation schemes.

That is, in the case where unlocking is impossible with demodulation by the BPSK and QPSK modulation schemes, the modulation scheme detection time is reduced by selecting the modulation scheme detection 501 from the 8PSK demodulation capable of detecting all modulation schemes.

6 is a view showing a modulation detection waveform according to a modulation method change according to the present invention. When the present invention is implemented by a signal processing work system (SPW), demodulation according to a selected modulation method is performed. The simulation result of the demodulated signal is shown.

The demodulator receives a modulated signal modulated according to a control signal 603 for modulating 8PSK, QPSK, BPSK in units of 50,000 samples, and demodulates the demodulated signal 602 by a demodulator 303. The frame synchronization detection result 601 detected by the signal is output.

The modulation scheme detection simulation result 604 from the demodulated signal 602 is accurately detected within 330 symbols (5.16us) after the modulation scheme is changed.

That is, the modulation scheme detection simulation result 604 from the demodulated signal 602 is almost identical to the control signal 603 for modulating in the modulation apparatus, and as described above, the demodulation by the modulation scheme detection is very fast. You can see that you have the ability.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention does not transmit the modulation scheme information of the transmitting side to the receiving side, and the receiving side does not need to include a plurality of demodulation means assuming all the modulation schemes. By detecting the direct modulation scheme, there is no need for a separate apparatus for providing modulation scheme information to the receiver at the transmitting side, and there is an effect that the demodulation apparatus can be simply implemented at the receiving side.

In addition, the present invention can detect the modulation method directly from the demodulated signal using the modulation method detection means, there is no need for an additional transmission channel for transmitting the separate modulation method information, there is an effect that can improve the efficiency of the bandwidth .

Claims (7)

A demodulation device using channel adaptive modulation detection, Receiving means for receiving a signal modulated by a channel adaptive modulation scheme from the outside; Demodulation means for demodulating a modulated signal from said receiving means in accordance with modulation scheme information; Modulation scheme detection means for detecting mapping information from the signal demodulated by the demodulation means to determine modulation scheme information and outputting the modulation scheme information to the demodulation means; And Decoding means for error correcting and decoding the demodulated signal from said demodulation means using modulation method information from said modulation method detection means. Demodulation device using a channel adaptive modulation scheme detection comprising a. The method of claim 1, The demodulation means, Demodulates a modulated signal received from the receiving means according to the modulation method information received from the modulation method detecting means, outputs a demodulated signal to the modulation method detecting means and the decoding means, and outputs the decision signal determined from the demodulation signal. Output to the method detection means, The modulation method detection means, And receiving the demodulation signal demodulated by the demodulation means and the determination signal determined from the demodulation signal, detecting mapping information to determine modulation method information, and then outputting the modulation method information to the demodulation means and the decoding means. Demodulation device using adaptive modulation detection. The method of claim 2, The modulation method detection means, A plurality of mapping information detection means for receiving a determination signal from the demodulation means and detecting a mapping signal at each constellation point; Demodulation state detection means for receiving demodulation signal and determination signal from said demodulation means and detecting demodulation state information; And Modulation method determination means for determining a modulation method by receiving each mapping signal detected by the plurality of mapping information detection means and demodulation state information detected by the demodulation state detection means; Demodulation device using a channel adaptive modulation scheme detection comprising a. The method of claim 3, wherein The plurality of mapping information detection means, A mapping detector at an 8PSK constellation point for receiving a determination signal from the demodulation means to detect a mapping signal at an 8PSK constellation point; A mapping detector at a QPSK constellation point for receiving a determination signal from the demodulation means and detecting a mapping signal at a QPSK constellation point; And A mapping detector at the BPSK constellation point for receiving the determination signal from the demodulation means and detecting the mapping signal at the BPSK constellation point. Demodulation device using channel adaptive modulation detection comprising a. The method of claim 4, wherein The modulation method determining means, A first logical sum operator configured to receive a QPSK mapping signal from the mapping detector at the 8PSK constellation point and a QPSK mapping signal from the mapping detector at the QPSK constellation point and select a QPSK modulation scheme; A second logical sum for receiving a BPSK mapping signal from the mapping detector at the 8PSK constellation point, a BPSK mapping signal from the mapping detector at the QPSK constellation point and a BPSK mapping signal from the mapping detector at the BPSK constellation point; An operator; And A modulation scheme determiner for determining a modulation scheme by receiving an 8PSK mapping signal from a mapping detector, a selection signal from the first and second logical sum operators, and demodulation state information detected by the demodulation state detection means at the 8PSK constellation point. Demodulation device using channel adaptive modulation detection comprising a. A demodulation method using channel adaptive modulation detection, Receiving a signal modulated by a channel adaptive modulation scheme; Demodulating the received modulated signal according to modulation scheme information; A modulation scheme detection step of detecting mapping information from the demodulated signal to determine and feedback modulation scheme information; And Decoding step of error correction and decoding the demodulated demodulated signal using the determined modulation scheme information Demodulation method using channel adaptive modulation detection comprising a. The method of claim 6, The modulation method detection step, Accumulating constellation points of the determination signal determined from the demodulation signal and detecting mapping information; And Determining a corresponding modulation method as the mapping information detection result is greater than or equal to a threshold value; Demodulation method using channel adaptive modulation detection comprising a.

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