KR100278312B1 - Mixed Modulation and Demodulation Method and Base Station and Subscriber - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a mixed modulation and demodulation method and a base station apparatus and a subscriber apparatus using the same.

2. The technical problem to be solved by the invention

The present invention transmits a signal using a mixture of QPSK and 16-QAM modulation scheme in a wireless subscriber network system, and the signal is transmitted to a subscriber device using a mixture of QPSK and 16-QAM demodulation scheme, thereby improving the efficiency of using the frequency. It is an object of the present invention to provide a mixed modulation and demodulation method and a base station apparatus and a subscriber apparatus using the same.

3. Summary of Solution to Invention

The present invention includes a first step of detecting a power of a received signal, and then determining a carrier-to-noise ratio for the received signal using the detected power detection value; Subtracting a predetermined reference value from the determined carrier-to-noise ratio; And a third step of controlling the modulation scheme according to whether the subtracted subtraction value is smaller than a predetermined value.

4. Important uses of the invention

The present invention is used in a broadband wireless subscriber network system.

Description

Mixed Modulation and Demodulation Method and Base Station and Subscriber

The present invention relates to a mixed modulation and demodulation method in a broadband wireless local loop (B-WLL) system, and a base station apparatus and a subscriber apparatus using the same. Particularly, a quadrature phase in a base station apparatus according to reception sensitivity according to a distance Shift Keying) A mixed modulation and demodulation method for transmitting and receiving a signal using a combination of a 16-QAM (quadrature amplitude modulation) modulation scheme and a subscriber device receiving the same by using a mixture of a QPSK demodulation scheme and a 16-QAM demodulation scheme. And a base station apparatus and a subscriber apparatus using the same.

In general, a broadband wireless subscriber network system (B-WLL) uses one modulation method, and a broadband wireless subscriber network system using a QPSK modulation scheme uses a 16-QAM modulation scheme when the output power of the same base station is used. The cell radius is larger than the broadband wireless subscriber network system used, but the spectral efficiency (bps / Hz) is lowered, which is much higher than that of the 16-QAM modulation system using the same bandwidth. There was a problem of transmitting less data.

On the other hand, the wideband wireless subscriber network system using the 16-QAM modulation scheme requires a higher signal to noise ratio (SNR) value although the spectral efficiency is higher than that of the wideband wireless subscriber network system using QPSK. There is a problem that the radius is much smaller than the broadband wireless subscriber network system using the QPSK modulation scheme.

Accordingly, the present invention has been made to solve the above problems, and by using a combination of QPSK modulation method and 16-QAM modulation method in a broadband wireless subscriber network system to transmit a signal, the utilization efficiency of the transmission frequency is significantly increased. One purpose is to provide a hybrid modulation method and a base station apparatus using the same.

In addition, the present invention provides a mixed demodulation method that can significantly increase the utilization efficiency of the reception frequency by receiving a signal transmitted from the base station apparatus using a mixed modulation scheme by using a mixture of the QPSK demodulation scheme and the 16-QAM demodulation scheme, and Another object is to provide a subscriber device using the same.

1 is an exemplary diagram showing a cell radius according to a modulation method of a base station apparatus of a broadband wireless subscriber network system to which the present invention is applied.

2 is a block diagram of an embodiment of a base station apparatus using a mixed modulation method according to the present invention;

3 is a flowchart of an embodiment of a mixed modulation method of a base station apparatus according to the present invention;

4 is a block diagram of an embodiment of a subscriber device using the mixed demodulation method according to the present invention;

5 is a flowchart illustrating an embodiment of a method for mixing demodulation of a subscriber device according to the present invention.

Explanation of symbols on the main parts of the drawings

110: transmission processor of base station apparatus 111: multiple QPSK modulators

112: multiple 16-QAM modulator 113: multiple frequency band switching section

114: signal combiner 115: up-converter

116: amplifier 120: reception processing unit of base station apparatus

121: low noise amplifier 122: down converter

123: signal distributor 124: multiple signal selector

125: power detector 126: multiple DQPSK demodulator

130: ATM switch 140: modulation control unit

150: base station controller 410: reception processing unit of subscriber station

411: low noise amplifier 412: down converter

413: signal selection unit 414: switching unit

415: QPSK demodulator 416: 16-QAM demodulator

417: demultiplexer 420: transmission processor of subscriber station

421: DQPSK modulator 422: frequency band switch

423: up-conversion unit 424: amplifier

430: subscriber interface 440: demodulation control unit

450: duplexer

In order to achieve the above object, the present invention provides a mixed modulation method for controlling a modulation method of a base station apparatus, wherein after detecting power of a received signal, a carrier-to-noise ratio of the received signal is detected by using the detected power detection value. Determining a first step; A second step of subtracting a predetermined reference value from the carrier-to-noise ratio determined in the first step; And a third step of controlling the modulation scheme according to whether the subtracted value subtracted in the second step is smaller than a predetermined value.

The present invention provides a base station apparatus including data processing means and modulating a signal to a subscriber device, wherein the signal transmitted from the data processing means is modulated by a selected modulation scheme, and then up-converted into a high frequency signal. Transmission processing means for transmitting to the apparatus; Reception processing means for down-converting the signal transmitted from the subscriber apparatus into a low frequency signal, distributing the signal into a plurality of signals, detecting power of the divided signals, and demodulating the divided signals; Modulation control means for receiving the power detection value detected by the reception processing means and providing modulation control information for controlling a modulation scheme of the transmission processing means; Switching means for switching a signal transmitted from the data processing means to the transmission processing means and a signal transmitted from the reception processing means to the data processing means under control of a base station control means; And the base station control means for controlling the switching means according to the modulation control information to select a modulation scheme of the transmission processing means, wherein the transmission processing means is configured to first modulate a plurality of signals transmitted from the switching means. A plurality of first modulating means for modulating in a controlled manner; A plurality of second modulating means for modulating a plurality of signals transmitted from said switching means in a second modulation scheme; A plurality of frequency band switching means for switching frequency bands of signals modulated by the plurality of first and second modulation means; Signal combining means for combining signals whose frequency band is switched by the plurality of frequency band switching means; And upconverting means for upconverting the output signal of the signal combining means into a high frequency signal and transmitting the converted signal to the subscriber device.

The present invention provides a mixed demodulation method of a subscriber apparatus for controlling a demodulation scheme for a signal received from a base station apparatus, the method comprising: a first step of receiving a signal transmitted from the base station apparatus; A second step of receiving information on a modulation scheme in the base station apparatus carried in the signal received from the base station apparatus; And a third step of controlling a demodulation scheme of the subscriber device by using the information on the modulation scheme.

The present invention provides a subscriber apparatus comprising a connecting means and signal processing means connected to the connecting means, the subscriber apparatus receiving a signal transmitted from a base station apparatus and transmitting a signal to the base station apparatus, wherein the signal received from the base station apparatus is downlinked. Reception processing means for demodulating the demodulation scheme in a selected demodulation scheme and transferring the demodulation scheme to the access means; Transmission processing means for modulating a signal transmitted from said signal processing means through said connection means and transmitting it to said base station apparatus; And demodulation control means for receiving information on the modulation scheme in the base station apparatus transmitted through the access means, and controlling demodulation scheme of the reception processing means, wherein the reception processing means is received from the base station apparatus. Downconversion means for downconverting the signal into a low frequency signal; Signal selection means for selecting and outputting a signal of a desired frequency band from the low frequency signals down-converted by the down conversion means; Switching means for selectively switching an output signal of the signal selecting means, according to the control of the demodulation controlling means; First demodulation means for demodulating the signal transmitted from the switching means in a first demodulation scheme; Second demodulation means for demodulating the signal transmitted from the switching means in a second demodulation scheme; And demultiplexing means for demultiplexing the signals transmitted from the first and second demodulating means to the connection means under control of the demodulation control means.

The present invention is a conventional base station apparatus using only one modulation and demodulation method by using a combination of the QPSK modulation and 16-QAM modulation and demodulation method according to the reception sensitivity according to the distance of the B-WLL (B-WLL) system In order to increase the frequency utilization efficiency, the spectral efficiency should be considered by comparing the cell size and area width that each modulation scheme can accommodate.

After dividing the frequency band for each modulation scheme in consideration of such a matter, information on the modulation scheme should be exchanged between the base station apparatus and the subscriber apparatus. For this purpose, a message about the setting of the modulation scheme is indicated in the control message of the broadband wireless subscriber network system. Must be added.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

In case of using QPSK modulation in order to receive high quality service in wireless subscriber network system, carrier to noise ratio (C / N) should be 15dB. In case of using 16-QAM modulation, carrier band The noise ratio should be 22dB.

Here, in consideration of the availability of the link, the carrier-to-noise ratio is about twice as large as the case of using the 16-QAM modulation scheme when the QPSK modulation scheme is used.

In such a case, it is possible to calculate the area of the region using the 16-QAM modulation scheme and the region using the QPSK modulation scheme.

That is, as shown in Figure 1, if the area using the 16-QAM modulation method is called A area, the area of A area is πγ ² In addition, if the area using the QPSK modulation method is called the area B, the area of the area B is the area that receives the QPSK modulation method minus the area that accepts the 16-QAM modulation method. π (2γ) ² - πγ ² = 3 πγ ² to be.

As described above, the area accommodating the QPSK modulation scheme in one cell is about three times wider than the area using the 16-QAM modulation scheme.

In conclusion, in one cell, (AREA _QPSK ) = 3 × AREA _16-QAM . Here, AREA _QPSK is the area of the area that accommodates the QPSK modulation scheme, and AREA _16-QAM is the area of the area that accommodates the 16-QAM modulation scheme.

Next, spectral efficiency to be considered is the spectral efficiency when using the QPSK modulation scheme is 1.5bps / Hz, and the spectral efficiency when using the 16-QAM modulation scheme is 3.5bps / Hz.

In addition, when the 16-QAM modulation method is used, the same data can be transmitted 2.3 times faster than when the QPSK modulation method is used, thereby increasing the frequency utilization efficiency by 2.3 times.

In other words, in order to transmit the same amount of data, an area using QPSK modulation is required 2.3 times more than an area using 16-QAM modulation.

Considering the two cases described above, the area accommodating the QPSK modulation scheme of one cell is three times wider than the area accommodating the 16-QAM modulation scheme, and the 16-QAM modulation scheme is used to transmit the same amount of data. Since the frequency bandwidth required is 2.3 times larger than the receiving area, the bandwidth ratio of the region using the QPSK modulation method and the 16-QAM modulation method is the area ratio and the modulation efficiency of the region using the QPSK modulation method and the 16-QAM modulation method. It can be expressed as the product of ratios. In other words, the bandwidth ratio is (1: 3) x (1: 2.3) = 1: 7.

In order to transmit data at the same rate to subscribers evenly distributed in each region in one cell, an area using QPSK modulation requires about 7 times wider bandwidth than an area using 16-QAM modulation. Shall be.

That is, the case of using the STM-4 (622.080 Mbps) to access the base station and the wireless subscriber network to obtain a specific frequency bandwidth as follows.

622.080 Mbps = BW _QPSK x 1.5bps + BW _16-QAM x 3.5bps. Here, BW _QPSK is the frequency bandwidth of the region using the QPSK modulation scheme, BW _16-QAM is the frequency bandwidth of the region using the 16-QAM modulation scheme.

However, a, BW _QPSK = 7 × Since _{BW 16-QAM, 622.08Mbps = 7BW} 16-QAM × 1.5bps + BW 16-QAM × 3.5bps = 14bps × BW 16-QAM.

Therefore, when using STM-4 in one cell, the BW _16-QAM becomes about 44.43 MHz.

The BW _QPSK will then have a bandwidth of 311.04 MHz, seven times the BW _16-QAM .

As such, assuming that BW _16-QAM can be about 45 MHz.

However, the BW _QPSK cannot modulate the 311.04MHz band on one channel, so it must be modulated by dividing into multiple channels.

Therefore, the 16-QAM modulation scheme is divided into seven channels with a bandwidth of 45 MHz, which is the local bandwidth, so it is good to allocate a channel even if the entire downlink frequency band is allocated to the operator by using the same bandwidth. In addition, even if the number of subscribers is required to increase the bandwidth, it may be increased considering the ratio of 1: 7 as described above.

As described above, in transmitting the data to the subscribers by setting the channel bandwidth, the base station apparatus should determine the reception mode of each subscriber to determine whether the modulation scheme is the QPSK modulation scheme or the 16-QAM modulation scheme.

2 is a block diagram of an embodiment of a base station apparatus using a mixed modulation method according to the present invention.

As shown in FIG. 2, the base station apparatus using the mixed modulation method according to the present invention includes a transmission processor 110 for transmitting data to a subscriber apparatus through an attached transmission antenna and a signal transmitted from the subscriber apparatus. The receiving processor 120 for receiving through the attached receiving antenna and the downlink data transmitted from the data processor (not shown) are switched to the transmitting processor 110 and the uplink data transmitted from the receiving processor 120 is recalled. Asynchronous Transfer Mode (ATM) switch 130 for switching to the data processing unit, modulation control unit 140 for controlling the modulation method of the transmission processing unit 110, and modulation control transferred from the modulation control unit 140 It is provided with a base station controller 150 for receiving the information to control the ATM switch 130.

The transmission processor 110 includes a plurality of QPSK modulators 1 to n 111 that modulate downlink data transmitted through the ATM switch 130 in a QPSK modulation scheme, and downlink transmitted through the ATM switch 130. Modulated by a plurality of 16-QAM modulators (1 to n) 112 and a plurality of QPSK modulators 111 and a plurality of 16-QAM modulators 112 that modulate data in a 16-QAM modulation scheme. Signal combining unit for combining the frequency band switching unit (1 to 2n) 113 for switching the frequency band of the signal, and the signals whose frequency band is switched by the plurality of frequency band switching unit 113 An up-transformer 115 for up-converting the signal coupled by the signal combiner 114 to a high-frequency signal, and an amplifier for amplifying the high-frequency signal up-converted by the up-converter 115. 116.

The reception processor 120 includes a low noise amplifier 121 for amplifying a high frequency signal received through a reception antenna, a down converter 122 for down converting a high frequency signal amplified by the low noise amplifier 121, and a down converter. The signal distributor 123 for distributing the signal converted by the converter 122 into a plurality of signals and the signals distributed by the signal distributor 123 are respectively input to select and output signals of a desired frequency band. A plurality of signal selectors 1 to n 124, a power detector 125 that detects and transmits power of signals output from the signal selector 124 to the modulation controller 140, and a signal selector A plurality of DQPSK demodulators (1 to n) 126 are provided to demodulate signals output from 124 in a differential quadrature phase shift keying (DQPSK) demodulation scheme, and then deliver them to the ATM switch 130.

The operation of the base station apparatus using the hybrid modulation method according to the present invention having the structure as described above will be described in detail as follows.

First, the data transmission process of the said transmission process part is demonstrated.

The ATM switch 130 under the control of the base station controller 150 selectively switches the downlink data transmitted from the data processor to the plurality of QPSK modulators 111 and the plurality of 16-QAM modulators 112.

Here, the base station controller 150 controls the ATM switch 130 according to the modulation control information transmitted from the modulation control unit 140 to select a modulation method, where the modulation control unit 140 is selected by the power detection unit 125. A process of controlling the modulation scheme by receiving the detected power detection value will be described in detail with reference to FIG. 3.

At this time, when the ATM switch 130 switches the downlink data transmitted from the data processor under the control of the base station controller 150 to the plurality of QPSK modulators 111, the plurality of QPSK modulators 111 transmits the downlink data. Is modulated by a QPSK modulation scheme and transmitted to the plurality of frequency band switching units 1 to n.

As such, the frequency band of the signal modulated by the plurality of QPSK modulators 111 is converted to a higher frequency band through the plurality of frequency band switching units 1 to n, and then in the signal combining unit 114. The signal is combined into one signal and transmitted to the up-converter 115.

Subsequently, the signal combined by the signal combiner 115 is up-converted into the high frequency signal by the up-converter 115, and then amplified by the amplifier 116 and transmitted to the subscriber device through the transmit antenna.

Meanwhile, when the ATM switch 130 is controlled by the base station controller 150 to switch the downlink data transmitted from the data processor to the plurality of 16-QAM modulators 112, the plurality of 16-QAM modulators 112 The transmitted downlink data is modulated by the 16-QAM modulation scheme and transmitted to the plurality of frequency band switching units n + 1 to 2n.

As such, the frequency band of the signal modulated by the plurality of 16-QAM modulators 112 is converted to a higher frequency band through the plurality of frequency band switching units n + 1 to 2n, and then, as described above. The same process is sent to the subscriber device.

Next, a process of receiving a signal transmitted from the subscriber device will be described.

When the high frequency signal transmitted from the subscriber device is received through the receiving antenna of the base station apparatus and amplified by the low noise amplifier 121, the downconversion unit 122 downwards the high frequency signal amplified by the low noise amplifier 121 to the low frequency signal. The signal is transferred to the signal distribution unit 123.

In this way, when the low frequency signal down-converted by the down converter 122 is divided into a plurality of signals through the signal distributor 123 and then transferred to the plurality of signal selectors 124, the plurality of signal selectors 124 ) Selects and outputs a signal of a desired frequency band from among the signals distributed by the signal distributor 123.

Subsequently, the power detector 125 detects the power of the signals selected by the plurality of signal selectors 124 and transmits the power to the modulation controller 140, and the plurality of DQPSK demodulators 126 are each a signal selector 124. The signals output from the DQPSK demodulation method are demodulated and then transferred to the ATM switch 130.

The upstream data transmitted to the ATM switch 130 through this process is delivered to the data processor.

3 is a flowchart illustrating an embodiment of a mixed modulation method of a base station apparatus according to the present invention.

Referring to FIG. 3, the reference value [C / N] ₀ for the carrier-to-noise ratio set in the modulation controller 140 is set to 22 dB (301).

The modulation controller 140 receives the power detection value of the received signal detected by the power detector 125 to determine the carrier-to-noise ratio [C / N] _d for the received signal (302), thereby determining the carrier-to-noise ratio. After subtracting 22 dB which is a reference value [C / N] ₀ which is preset at [C / N] _d (303), it is determined whether the subtracted value S is smaller than '0' (304).

At this time, if it is determined that the subtracted value S is smaller than '0' in the size determination process 304 of the subtracted value S, the carrier-to-noise ratio [C / N] _d is greater than 22 dB which is the reference value [C / N] ₀ . As such, the modulation controller 140 transmits modulation control information for modulating the signal by the QPSK modulation scheme to the base station controller 150 (305).

Accordingly, the base station controller 150 switches the ATM switch 130 to a plurality of QPSK modulators 111.

On the other hand, if it is determined that the subtracted value S is not smaller than '0' in the magnitude determination process 304 of the subtracted value S, the carrier-to-noise ratio [C / N] _d is smaller than 22 dB which is the reference value [C / N] ₀ . Since it is not large, the modulation controller 140 transmits modulation control information for modulating a signal by the 16-QAM modulation scheme to the base station controller 150 (306).

Similarly, base station controller 150 switches ATM switch 130 to multiple 16-QAM modulators 112.

4 is a block diagram of an embodiment of a subscriber device using the mixed demodulation method according to the present invention.

As shown in FIG. 4, the subscriber apparatus using the mixed demodulation method according to the present invention includes a reception processor 410 for receiving a signal transmitted from the base station apparatus through an attached transmit / receive antenna, and a signal processor (not shown). And a transmission processor 420 for transmitting a signal transmitted from the signal processor to the base station apparatus, and a signal transmitted from the reception processor 410 to the signal processor. A demodulation control unit 440 for controlling the demodulation method of the reception processing unit 410 by receiving the modulation information of the base station apparatus from the subscriber interface 430, and a reception antenna through a transmission / reception antenna. Transmits the received signal to the receiving processor 410 and transmits the signal transmitted from the transmitting processor 420 to the base station through a transmitting and receiving antenna. And a duplexer 450 for transmitting to the device.

The reception processor 410 includes a low noise amplifier 411 for amplifying a signal received through the duplexer 450, a down converter 412 for down converting a signal amplified by the low noise amplifier 411, and A signal selector 413 that receives the signal converted by the down converter 412 and selects and outputs a signal having a desired frequency band, and an output signal of the signal selector 413 under the control of the demodulation controller 440. 16-QAM demodulation for the switching unit 414 for selectively switching the signal, the QPSK demodulator 415 for demodulating the signal transmitted from the switching unit 414 in a QPSK demodulation scheme, and the signal transmitted from the switching unit 414. 16-QAM demodulator 416 for demodulating in a manner, and demultiplexer 417 for demultiplexing signals transmitted from QPSK demodulator 415 and 16-QAM demodulator 416 under the control of demodulation control unit 440. It is provided.

Here, the reception processing unit 410 is configured to demodulate a signal received from the base station apparatus in a QPSK demodulation scheme in an initial state.

The transmission processor 420 switches the frequency band of the signal modulated by the DQPSK modulator 421 and the DQPSK modulator 421 to modulate the signal transmitted from the signal processor through the subscriber interface 430 by the DQPSK modulation scheme. A frequency band switching unit 422, an up-converting unit 423 for up-converting a signal whose frequency band is switched through the frequency band switching unit 422, to a high frequency signal, and an up-converting unit 423 And an amplifier 424 for amplifying the high frequency signal.

Referring to the operation of the subscriber device using the mixed demodulation method according to the present invention having the structure as described above in detail as follows.

First, a process of receiving a signal transmitted from the base station apparatus will be described.

When the signal received from the base station apparatus through the duplexer 450 is amplified by the low noise amplifier 411 and transferred to the down converter 412, the down converter 412 is a signal amplified by the low noise amplifier 411. Down-converts the signal to a low-frequency signal and delivers the signal to the signal selector 412.

As such, when a signal having a desired frequency band among the signals converted by the down converter 412 is selected by the signal selector 413 and then transferred to the switching unit 414, the switching unit 414 is demodulated control unit 440. Under the control, the output signal of the signal selector 413 is selectively switched to the QPSK demodulator 415 and the 16-QAM demodulator 416. However, in the initial state, the output signal of the signal selector 413 is demodulated by the QPSK demodulator 415.

Here, when the switching unit 414 switches the output signal of the signal selection unit 414 to the QPSK demodulator 415 under the control of the modulation control unit 440, the QPSK demodulator 415 converts the transmitted signal into the QPSK demodulation scheme. The demodulator transmits the demodulated signal to the demultiplexer 417.

In this case, the subscriber interface 430 connects the information on the modulation scheme of the base station apparatus transmitted from the reception processor 410 to the demodulation control unit 440. The modulation control unit 440 receives the modulation information and receives the switching unit. The demodulating method is selected by controlling the switching operation of 414.

That is, if the signal currently received from the base station apparatus is a signal modulated by the QPSK modulation scheme, the demodulation controller 440 switches the switching unit 414 to the QPSK demodulator 415 so that the received signal is demodulated by the QPSK demodulation scheme. do.

If the signal currently received from the base station apparatus is a signal modulated by the 16-QAM modulation scheme, the demodulation controller 440 switches the switching unit 414 to the 16-QAM demodulator 416 so that the received signal is 16-. Demodulate using QAM demodulation.

Subsequently, the demultiplexer 417 demultiplexes the signal demodulated by the QPSK demodulator 415 under the control of the modulation controller 440, and transmits the demultiplexed signal to the signal processor through the subscriber interface 430.

On the other hand, when the switching unit 414 switches the output signal of the signal selection unit 414 to the 16-QAM demodulator 416 under the control of the modulation control unit 440, the 16-QAM demodulator 416 receives the transmitted signal. Demodulate in 16-QAM demodulation.

As such, the signal demodulated by the 16-QAM demodulation method is transferred to the signal processor through the above-described process.

The process of the demodulation control unit 440 controlling the demodulation method will be described in detail with reference to FIG. 5.

Next, a process of transmitting a signal transmitted from the signal processor of the subscriber device to the base station apparatus will be described.

When the signal output from the signal processor is transferred to the DQPSK modulator 421 through the subscriber interface 430, the DQPSK modulator 421 modulates the transmitted signal by the DQPSK modulation scheme and transmits the signal to the frequency band switcher 422. .

When the frequency band of the modulated signal is converted to a higher frequency band through the frequency band switcher 422 and then transferred to the upconverter 115, the upconverter 423 converts the transmitted signal into a high frequency signal. Up-converts it to the amplifier 424.

Subsequently, the amplifier 424 transmits the high frequency signal up-converted by the up-converter 423 to the duplexer 450 to be transmitted to the base station apparatus through the transmit / receive antenna.

5 is a flowchart illustrating an embodiment of a mixed demodulation method of a subscriber device according to the present invention.

Referring to FIG. 5, in an initial state, the reception processing unit 410 demodulates a signal received from the base station apparatus by QPSK demodulation and transmits the signal to the subscriber interface 430 (501).

In addition, the demodulation control unit 440 receives information on the modulation scheme of the base station apparatus delivered through the subscriber interface 430 (402), and whether the signal is modulated by the QPSK modulation scheme or 16-QAM in the base station apparatus. In operation 503, if the signal is modulated by the QPSK modulation method, the demodulation control unit 440 switches the switching unit 414 to the QPSK demodulator 415 to receive the signal from the base station apparatus. The demodulated signal is demodulated by the QPSK demodulator 415 in a QPSK demodulation scheme (504).

On the other hand, in the step 503 of determining the modulation scheme of the base station apparatus, if the signal is modulated by the 16-QAM modulation scheme in the base station apparatus, the demodulation control unit 440 switches the switching unit 414 to the 16-QAM demodulator ( 416, the signal received from the base station apparatus is demodulated in a 16-QAM demodulation scheme via a 16-QAM demodulator 416 (505).

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention transmits a signal using a mixture of the QPSK modulation method and the 16-QAM modulation method in a broadband wireless subscriber network system, and the transmitted signal is transmitted to the subscriber station by the QPSK demodulation method and the 16-QAM demodulation method. By using the mixed reception, the amount of data to be transmitted increases so that the frequency can be effectively used. Especially, the cell radius (that is, the area covered by the base station) is much wider than that of the wireless subscriber network system using only one method. Accordingly, there is a very good effect that the capacity of the subscriber is significantly increased.

Claims (10)

In the mixed modulation method for controlling the modulation method of the base station apparatus, A first step of determining a carrier-to-noise ratio for the received signal using the detected power detection value after detecting the power of the received signal; A second step of subtracting a predetermined reference value from the carrier-to-noise ratio determined in the first step; And A third step of controlling the modulation scheme according to whether the subtracted value subtracted in the second step is smaller than a predetermined value; Mixed modulation method of a base station device comprising a. The method of claim 1, The third step, A fourth step of determining whether the subtracted value is smaller than the predetermined value '0'; A fifth step of modulating a signal by a quadrature phase shift keying (QPSK) modulation method when it is determined that the subtraction value is smaller than '0' as a result of the determination in the step 4; And A sixth step of modulating the signal by a 16-QAM (Quadrature Amplitude Modulation) modulation method when it is determined in the step 4 that the subtraction value is not smaller than '0' Mixed modulation method of a base station device comprising a. A base station apparatus comprising data processing means and modulating and transmitting a signal to a subscriber apparatus and receiving a signal transmitted from the subscriber apparatus, Transmission processing means for modulating a signal transmitted from the data processing means with a selected modulation scheme and then up-converting the high frequency signal to the subscriber device; Reception processing means for down-converting the signal transmitted from the subscriber apparatus into a low frequency signal, distributing the signal into a plurality of signals, detecting power of the divided signals, and demodulating the divided signals; Modulation control means for receiving the power detection value detected by the reception processing means and providing modulation control information for controlling a modulation scheme of the transmission processing means; Switching means for switching a signal transmitted from the data processing means to the transmission processing means and a signal transmitted from the reception processing means to the data processing means under control of a base station control means; And The base station control means for controlling the switching means according to the modulation control information to select a modulation method of the transmission processing means, The transmission processing means, A plurality of first modulating means for modulating a plurality of signals transmitted from said switching means in a first modulation scheme; A plurality of second modulating means for modulating a plurality of signals transmitted from said switching means in a second modulation scheme; A plurality of frequency band switching means for switching frequency bands of signals modulated by the plurality of first and second modulation means; Signal combining means for combining signals whose frequency band is switched by the plurality of frequency band switching means; And Up-converting means for up-converting the output signal of the signal combining means to a high-frequency signal and transmitting it to the subscriber device Base station apparatus using a mixed modulation method comprising a. The method of claim 3, wherein The reception processing means, Amplifying means for amplifying a signal transmitted from the subscriber device; Downconverting means for downconverting the signal amplified by the amplifying means into a low frequency signal; Signal distributing means for distributing the down-converted signal by the down-converting means into a plurality of signals; A plurality of signal selection means for receiving a plurality of signals output from the signal distribution means and selecting and outputting signals of a desired frequency band; Power detecting means for receiving the output signals of the plurality of signal selecting means and detecting the power of the signal received from the subscriber apparatus and transmitting the detected power to the modulation control means; And A plurality of demodulation means for demodulating the signals output from the signal selection means in a differential quadrature phase shift keying (DQPSK) demodulation method to deliver to the switching means Base station apparatus using a mixed modulation method comprising a. The method according to claim 3 or 4, The first modulation scheme, Modulating a plurality of signals transmitted from the switching means in a quadrature phase shift keying (QPSK) modulation scheme, The second modulation scheme is, The base station apparatus using a mixed modulation method characterized in that for modulating a plurality of signals transmitted from the switching means in 16-QAM (Quadrature Amplitude Modulation). In the mixed demodulation method of the subscriber device for controlling the demodulation method for the signal received from the base station device, A first step of receiving a signal transmitted from the base station apparatus; A second step of receiving information on a modulation scheme in the base station apparatus carried in the signal received from the base station apparatus; And A third step of controlling a demodulation scheme of the subscriber device by using the information on the modulation scheme; Mixed demodulation method of the subscriber device comprising a. The method of claim 6, The third step, A fourth step of determining whether a signal in the base station apparatus is modulated by a Quadrature Phase Shift Keying (QPSK) modulation method or a 16-Quadrature Amplitude Modulation (QAM) modulation method using the information on the modulation scheme; A fifth step of demodulating the signal received from the base station apparatus in the QPSK demodulation scheme if the signal in the base station apparatus is modulated in the QPSK modulation scheme as a result of the determination in the fourth step; And A sixth step of demodulating the signal received from the base station apparatus in the 16-QAM demodulation scheme if the signal in the base station apparatus is modulated by the 16-QAM modulation scheme in the fourth step; Mixed demodulation method of the subscriber device comprising a. A subscriber apparatus comprising a connecting means and signal processing means connected to the connecting means, the subscriber apparatus receiving a signal transmitted from a base station apparatus and transmitting a signal to the base station apparatus, Receiving processing means for down-converting the signal received from the base station apparatus, demodulating the selected demodulation scheme and transmitting the demodulated signal to the access means; Transmission processing means for modulating a signal transmitted from said signal processing means through said connection means and transmitting it to said base station apparatus; And Demodulation control means for receiving information on the modulation scheme in the base station apparatus delivered through the access means and controlling a demodulation scheme of the reception processing means, The reception processing means, Downconversion means for downconverting the signal received from the base station apparatus into a low frequency signal; Signal selection means for selecting and outputting a signal of a desired frequency band from the low frequency signals down-converted by the down conversion means; Switching means for selectively switching an output signal of the signal selecting means, according to the control of the demodulation controlling means; First demodulation means for demodulating the signal transmitted from the switching means in a first demodulation scheme; Second demodulation means for demodulating the signal transmitted from the switching means in a second demodulation scheme; And Demultiplexing means for demultiplexing a signal transmitted from the first and second demodulating means and transmitting the demultiplexed signal to the connection means according to the control of the demodulation control means. Subscriber device using a mixed demodulation method comprising a. The method of claim 8, The transmission processing means, Modulation means for modulating a signal transmitted from the signal processing means through the connection means; Frequency band switching means for switching a frequency band of the signal modulated by the modulating means; Upconverting means for upconverting the output signal of the frequency band switching means into a high frequency signal; And Amplifying means for amplifying the output signal of the upconverting means and transmitting the amplified signal to the base station apparatus Subscriber device using a mixed demodulation method comprising a. The method according to claim 8 or 9, The first demodulation method, Demodulating the signal transmitted from the switching means in a quadrature phase shift keying (QPSK) demodulation scheme, The second modulation scheme is, And demodulating the signal transmitted from the switching means in a 16-QAM (Quadrature Amplitude Modulation) demodulation scheme.