KR20130106197A

KR20130106197A - Apparatus for wireless data transmission and method thereof

Info

Publication number: KR20130106197A
Application number: KR1020120027908A
Authority: KR
Inventors: 정길수; 김대호
Original assignee: 한국전자통신연구원
Priority date: 2012-03-19
Filing date: 2012-03-19
Publication date: 2013-09-27

Abstract

Disclosed are a wireless data transmission apparatus and a method thereof according to the present invention.
According to an aspect of the present invention, there is provided a wireless data transmission apparatus including: a sensing unit configured to detect an unused resource available in an available band of an operating frequency band based on a spectrum sensing technology; A controller for selecting a channel or a frequency band for wireless data transmission based on the detected unused resources and determining whether communication can be started through the selected channel; And a transmission unit for transmitting data through the channel when the communication can be started.

Description

Wireless data transmission apparatus and method thereof {APPARATUS FOR WIRELESS DATA TRANSMISSION AND METHOD THEREOF}

The present invention relates to a wireless data transmission method, and in particular, it is possible to allocate available unused resources detected by detecting available unused resources of the operating frequency band through three-dimensional observation of the time axis, the space axis, and the frequency axis. The present invention relates to a wireless data transmission apparatus and a method for splitting a spectrum subjected to Single Carrier (SC) modulation into a plurality of bands and performing a frequency conversion on each of the divided bands.

At present, the shortage of frequency resources is increasing significantly with increasing demand for wireless data communication. In order to solve the shortage of frequency resources, researches and developments related to cognitive radio technologies that detect and use unused frequency resources of existing radio systems secondarily are being actively conducted.

Here, the cognitive radio technology refers to a technology that automatically finds unused frequencies according to a region and time, and makes a target communication possible while protecting a licensed radio station in the vicinity. That is, after finding a frequency channel that is not used when providing a service for each user, the found frequency channel is provided to a secondary user. For example, when providing a service based on wireless communication to a secondary user rather than a primary user, a time / spatial inspection of a frequency channel authorized to the primary user for service provision is performed. It finds unused frequency channels and provides them to the secondary user.

In order to realize this, a sensing technology for detecting available radio resources by observing the usage of the operating band, a media access control (MAC) and a PHY related technology for efficiently allocating and using the detected radio resources are important.

In addition, SDM (Spatial Division Multiplexing) using multiple antennas may be used as a method for sharing frequency resources. Interference avoidance is possible using such spatial multiplexing techniques.

However, when using this spatial multiplexing technique, the number of unused frequency resources is expected to remain because there is a limit in the number of spatial multiples, that is, the number of available antennas and the interference suppression capability. Therefore, a method for maximizing the efficient use of such unused frequency resources is required.

Accordingly, an object of the present invention is to solve the problems of the prior art, and an object of the present invention is to detect available unused resources of an operating frequency band through three-dimensional observation of a time axis, a space axis, and a frequency axis, and to allocate detected unused resources. The present invention provides a transmission device and a method thereof.

Another object of the present invention is to provide a wireless data transmission apparatus and method for splitting a spectrum subjected to Single Carrier (SC) modulation based on a detected result into a plurality of bands and then performing frequency conversion on each of the plurality of divided bands. To provide.

However, the objects of the present invention are not limited to those mentioned above, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above objects, the wireless data transmission apparatus according to an aspect of the present invention includes a sensing unit for detecting the unused resources available in the use band of the operating frequency band based on the spectrum sensing technology; A controller for selecting a channel or a frequency band for wireless data transmission based on the detected unused resources and determining whether communication can be started through the selected channel; And when the communication can be started, it may include a transmitter for transmitting data through the channel.

Preferably, the sensing unit may three-dimensionally observe the use band of the operating frequency band on the time axis, the space axis, and the frequency axis based on the spectrum sensing technology, and detect available unused resources according to the observed result.

Preferably, the controller determines whether communication can be initiated with a communication partner through a selected channel according to a predetermined criterion of whether communication can be initiated, wherein the criterion of whether communication can be started is based on a preset unused frequency band. It is characterized by using one of whether it is secured or whether it is possible to transmit by spatial multiplication using a multi-antenna technique.

According to another aspect of the present invention, an apparatus for transmitting wireless data includes an N-point DFT unit for performing discrete Fourier transform on parallel data for each divided frequency band; A spectrum mapping unit for mapping the plurality of data output from the N-point DFT unit to the center frequency of each divided frequency band; An M-point IFFT unit performing an inverse fast Fourier transform on the data output from the spectrum mapping unit; And a filtering unit which filters inverse fast Fourier transformed data from the M-point IFFT unit.

Preferably, the spectral mapping unit spreads the plurality of data output from the N-point DFT unit and maps the spread spectrum data to each divided center frequency corresponding to each divided frequency band. Can be.

Preferably, the filtering unit is characterized in that using a BPF (Band Pass Filter).

In addition, the wireless data transmission apparatus according to the present invention includes a P / S unit for converting the parallel data output from the filtering unit to serial data; And a DAC / RF unit for converting the digital data output from the P / S unit into analog data and transmitting the same through a selected channel.

According to another aspect of the present invention, a wireless data transmission device includes: a filtering unit for filtering the received data when receiving data through a previously selected channel; An M-point FFT unit performing fast Fourier transform on the data output from the filtering unit; A spectral demapping unit for demapping data output from the M-point FFT unit at each divided center frequency corresponding to each divided frequency band; And an N-point IDFT unit performing inverse discrete Fourier transform on the data output from the spectral inverse mapping unit.

Preferably, the spectral demapping unit demaps the data output from the M-point FFT unit at each of the divided center frequencies corresponding to each of the divided frequency bands and despreads the plurality of demapped data. have.

In addition, the wireless data transmission apparatus according to the invention RF / ADC unit for converting the analog data received through the antenna into digital data; And an S / P unit configured to convert the serial data converted into digital data into parallel data and output the parallel data to a filtering unit.

According to another aspect of the present invention, there is provided a method of transmitting wireless data, the method comprising: detecting unused resources available in an available band of an operating frequency band based on a spectrum sensing technique; Selecting a channel or frequency band for wireless data transmission based on the detected unused resources; Determining whether communication can be started through the selected channel; And when the communication can be started, transmitting data through the selected channel.

Preferably, the detecting may include three-dimensional observation of a use band of an operating frequency band on a time axis, a space axis, and a frequency axis based on the spectrum sensing technology to detect an unused resource available according to the observed result.

Preferably, the determining may determine whether to start communication with a communication partner through a selected channel according to a predetermined criterion of whether communication can be initiated, wherein the criterion of whether communication can be started is a preset unused frequency. It is characterized by using one of whether a band is secured or whether transmission is possible by spatial multiplexing using a multi-antenna technique.

Advantageously, the step of transmitting comprises: performing discrete Fourier transform on the parallel data for each divided frequency band; Mapping the plurality of discrete Fourier transformed data to a center frequency of each divided frequency band; Performing an inverse fast Fourier transform on the data mapped to the center frequency; Filtering the inverse fast Fourier transformed data; Converting the filtered parallel data into serial data; And converting the digital data converted into the serial data into analog data and transmitting the same through the channel.

The mapping may include spreading the plurality of discrete Fourier transform data and mapping the spread spectrum data to each divided center frequency corresponding to each divided frequency band.

In this way, the present invention has the effect of resolving the shortage of frequency resources by detecting available unused resources of the operating frequency band through three-dimensional observation of the time axis, space axis, and frequency axis, and allocating the detected unused resources. .

In addition, the present invention has the effect of maximizing the utilization efficiency of frequency resources by detecting the available unused resources of the operating frequency band by allocating the detected unused resources through the three-dimensional observation of the time axis, the spatial axis, and the frequency axis.

In addition, the present invention divides the SC-modulated spectrum into a plurality of bands based on the detected result and frequency-transmits each of the plurality of divided bands, thereby transmitting an Adjacent Channel Power Ratio (ACPR) and Peak-to-PAPR. Average Power Ratio) can be reduced.

1 illustrates a wireless data transmission apparatus according to an embodiment of the present invention.
2 is a diagram illustrating a process of determining communication start according to an embodiment of the present invention.
3 is a diagram illustrating a detailed configuration of the transmitter 140 illustrated in FIG. 1.
4 is a diagram illustrating a detailed configuration of the receiver 150 illustrated in FIG. 1.
5 is a first diagram illustrating a wireless data transmission method according to an embodiment of the present invention.
6 is a second diagram illustrating a wireless data transmission method according to an embodiment of the present invention.

Hereinafter, a wireless data transmission apparatus and a method thereof according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. The present invention will be described in detail with reference to the portions necessary for understanding the operation and operation according to the present invention. Like reference numerals in the drawings denote like elements throughout the specification. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In the present invention, 1) it is possible to allocate available unused resources by detecting available unused resources of the operating frequency band through 3D observation of time axis, space axis, and frequency axis, and 2) SC (Single Carrier) based on the detected result. The present invention proposes a method of dividing a modulated spectrum into a plurality of bands and performing a frequency conversion on each of the divided bands.

1 illustrates a wireless data transmission apparatus according to an embodiment of the present invention.

As shown in FIG. 1, a wireless data transmission apparatus according to the present invention may include a sensing unit 110, a storage unit 120, a control unit 130, a transmitter 140, a receiver 150, and the like. have.

The sensing unit 110 may detect the unused resources available according to the result of the observation by using three-dimensional observation of the use frequency of the operating frequency band, that is, the use band, based on the spectrum sensing technology. In this case, the sensing unit 110 may periodically check the use status of the operating frequency band or aperiodically as necessary.

Here, the spectrum sensing technique is a simulation that determines whether an available spectrum is occupied or used by the primary user or is part of a frequency that is not being used, so that the secondary user can use the idle frequency without interfering with the primary user. It refers to core frequency resource sharing technology. Spectrum sensing technology allows the secondary user to sense the spectrum of the surrounding environment to detect spectral holes not used by the primary user and temporarily use the channel while the primary user is not using the spectrum.

The controller 130 may select a channel or frequency band for wireless data transmission based on the detected available unused resources and divide the selected frequency band into a predetermined number.

The controller 130 may provide such frequency information to the transceiver. Here, the frequency information may include a use frequency band, a number of band divisions, a center frequency of each divided band, and the like.

2 is a diagram illustrating a process of determining communication start according to an embodiment of the present invention.

As shown in FIG. 2, the apparatus for transmitting wireless data according to the present invention is based on a spectrum sensing technique, and uses three-dimensional observations of a usage state of an operating frequency band, that is, a time axis, a space axis, and a frequency axis. Accordingly, available unused resources can be detected (S211).

The wireless data transmission device may check whether transmission data has occurred (S210).

Next, when the transmission data is generated, the wireless data transmission apparatus may acquire control information for sharing between the transceivers (S220). Here, the control information may include, for example, base station registration related information, reception wait, acquisition / notification of location information, allocation channel, modulation scheme, and the like.

Next, the wireless data transmission apparatus may select a channel or frequency band for wireless data transmission based on the detected available unused resources (S230).

The wireless data transmission device may determine the final channel by adjusting the selected channel with a communication counterpart.

Next, when the channel determination is completed, the wireless data transmission device may determine whether to start communication (S240). That is, the controller 130 determines whether communication with the communication partner through the selected final channel is possible or impossible according to a predetermined determination criterion. Here, the determination criteria may include, for example, whether a sufficient unused frequency band is secured for communication or whether transmission by spatial multiplexing using multiple antenna technology is possible.

Next, when the communication start is possible, the wireless data transmission apparatus starts communication with the communication counterpart (S250), and when the communication start is impossible, spectrum sensing is performed again.

When the communication unit 140 can start communication, the transmission unit 140 may transmit transmission data, and the reception unit 150 may receive the reception data from the communication partner who has received the transmission data.

In the wireless system according to the present invention, a basic configuration of a physical channel includes a control channel (CCH) and a data channel (DCH).

The control channel is a physical channel for sharing control information such as base station registration related information, reception standby, location information acquisition / notification, allocation channel, and modulation scheme between the transceivers. In the wireless data transmission apparatus according to the present invention, since there is no occupied frequency channel, an efficient transmission method of a control channel for sharing information between transceivers is an important problem, and this is directly related to DS-SS technology. It can be realized using multiple antenna technology.

The data channel detects unused radio resources of the existing radio system, aggregates fragmented unused frequency resources, and transmits them by using one radio channel. In other words, the transmission spectrum can be divided into a plurality of bands and discontinuously spectralized to be transmitted. As a conventional technique for realizing this, the frequency of an orthogonal frequency division multiple access (OFDMA) selectively using an orthogonal frequency division multiplexing (OFDM) subcarrier Scheduling method, and Discrete Frequency Transform (DFT) of SC (Discrete Frequency Transform) to map the discrete spectrum on the frequency axis and then transmit by Inverse Discrete Frequency Transform (IDFT) or Inverse Fast Fourier Transform (IFFT) And the like. The problem with the aforementioned schemes is that since existing wireless systems generally operate in adjacent channels, they have a large Adjacent Channel Power Ratio (ACPR), which directly affects the existing wireless system. In addition, due to the multicarrier transmission, there is a disadvantage of increasing the peak-to-average power ratio (PAPR).

To solve this problem, we propose a transceiver that can reduce ACPR and PAPR. In the proposed band-limited spectral division SC transmission method, SC modulation is performed based on the result of spectral sensing on the determined required bandwidth, and the spectrum is divided into a plurality of bands by using a band pass filter (BPF). It has a structure to transmit after conversion.

3 is a diagram illustrating a detailed configuration of the transmitter 140 illustrated in FIG. 1.

As shown in FIG. 3, the transmitter 140 according to the present invention includes a serial to parallel (S / P) unit 141, an N-point discrete fourier transform (DFT) unit 142, and a spectrum mapping unit (spectrum mapping). ) 143, M-point Inverse Fast Fourier Transform (IFFT) unit 144, filtering unit 145, P / S (Parallel to Serial) unit 146, DAC / RF (Digital to Analog Converter / Radio Frequency) The unit 147 may be configured to include the same.

The S / P unit 141 may convert the input serial data into parallel data.

The N-point DFT unit 142 may divide the converted parallel data by the number of band divisions and perform discrete Fourier transform on each divided frequency band. As shown in the figure, the case where the number of band divisions is set to four, for example, is described.

The spectrum mapping unit 143 spreads each of the four data output from the N-point DFT unit 142 and spreads the four spread data into unused frequency bands, i.e., each divided frequency band. That is, it can be mapped to each divided center frequency.

The M-point IFFT unit 144 may perform inverse fast Fourier transform on the data output from the spectrum mapping unit 143.

The filtering unit 145 may filter data output from the M-point IFFT unit 144. Here, the filtering unit 145 preferably uses a BPF (Band Pass Filter).

The P / S unit 146 may convert the parallel data output from the filtering unit 145 into serial data.

The DAC / RF unit 147 may convert digital data converted into serial data into analog data, and transmit the converted analog data through an antenna.

4 is a diagram illustrating a detailed configuration of the receiver 150 illustrated in FIG. 1.

As shown in FIG. 4, the receiver 150 according to the present invention includes an RF / ADC (Radio Frequency / Analog to Digital Converter) unit 151, an S / P (Serial to Parallel) unit 152, and a filtering unit ( 153), an M-point Fast Fourier Transform (FFT) unit 154, a spectral demapping unit 155, an N-point Inverse Discrete Fourier Transform (IDFT) unit 156, and P / S (Parallel to Serial) unit 157 and the like can be configured.

The RF / ADC unit 151 may receive analog data through an antenna and convert the received analog data into digital data.

The S / P unit 152 may convert serial data converted into digital data into parallel data.

The filtering unit 153 may filter data output from the S / P unit 152. Here, the filtering unit 153 preferably uses a BPF (Band Pass Filter).

The M-point FFT unit 154 may perform fast Fourier transform on the data output from the filtering unit 153.

The spectrum demapping unit 155 demaps the data output from the M-point FFT unit 154 at an unused frequency band, that is, an IFFT subcarrier corresponding to each divided frequency band, that is, each divided center frequency. Four mapped data may be despread.

The N-point IDFT unit 156 may perform inverse discrete Fourier transform on the data output from the spectral inverse mapping unit 155.

The P / S unit 157 may convert parallel data output from the N-point IDFT unit 156 into serial data.

5 is a first diagram illustrating a wireless data transmission method according to an embodiment of the present invention.

As shown in FIG. 5, the wireless data transmission apparatus according to the present invention converts serial data input for transmission into parallel data (S510), divides the converted parallel data into band division numbers, and divides them for each divided frequency band. A Fourier transform may be performed (S520).

Next, the wireless data transmission apparatus spreads a plurality of discrete Fourier transform data (S530) and spreads the spread spectrum data in an unused frequency band, that is, an IFFT subcarrier corresponding to each divided frequency band, that is, each division. It may be mapped to the center frequency (S540).

Next, the wireless data transmission apparatus may perform inverse fast Fourier transform on the mapped data (S550).

Next, the wireless data transmission device may filter the inverse fast Fourier transformed data (S560).

Next, the wireless data transmission device may convert the filtered parallel data into serial data (S570).

Next, the wireless data transmission device may convert the digital data converted into serial data into analog data (S580), and transmit the converted analog data through an antenna (S590).

6 is a second diagram illustrating a wireless data transmission method according to an embodiment of the present invention.

As shown in FIG. 6, the wireless data transmission apparatus according to the present invention may receive analog data through an antenna (S610) and convert the received analog data into digital data (S620).

Next, the wireless data transmission apparatus may convert serial data converted into digital data into parallel data (S630).

Next, the wireless data transmission device may filter the data converted into parallel data (S640).

Next, the wireless data transmission apparatus may perform fast Fourier transform on the filtered data (S650).

Next, the wireless data transmission apparatus reverse-maps the fast Fourier transformed data in an unused frequency band, that is, an IFFT subcarrier corresponding to each divided frequency band, that is, each divided center frequency (S660), The data may be deband spread (S670).

Next, the wireless data transmission apparatus may perform inverse discrete Fourier transform on the despread-spread data (S680).

Next, the wireless data transmission apparatus may convert inverse discrete Fourier transformed parallel data into serial data (S690).

Meanwhile, the above-described embodiments of the present invention can be implemented as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (e.g., ROM, floppy disk, hard disk, etc.), optical reading medium (e.g., CD ROM,

Those skilled in the art of the wireless data transmission apparatus and method according to the present invention will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas falling within the scope of the present invention should be construed as being included in the scope of the present invention.

110: sensing unit
120:
130:
140: transmitter
141: S / P part
142: N-point DFT section
143: spectrum mapping unit
144: M-point IFFT part
145: filtering unit
146: P / S section
147: DAC / RF section
150:
151: RF / ADC part
152: S / P part
153: filtering unit
154: M-point FFT part
155: spectrum reverse mapping unit
156: N-point IDFT unit
157: P / S section

Claims

A sensing unit that detects unused resources available in a use band of an operating frequency band based on a spectrum sensing technology;
A controller for selecting a channel or a frequency band for wireless data transmission based on the detected unused resources and determining whether communication can be started through the selected channel; And
A transmission unit for transmitting data through the channel when the communication can be started;
Wireless data transmission device comprising a.

The method according to claim 1,
The sensing unit includes:
And a three-dimensional observation of the use band of the operating frequency band based on the spectrum sensing technology on a time axis, a space axis, and a frequency axis, and detects unused resources available according to the observed result.

The method according to claim 1,
The control unit,
It is determined whether to start communication with a communication partner through a selected channel according to a predetermined criterion of whether communication can be started.
Here, the criterion for determining whether the communication can be started is one of whether a predetermined unused frequency band is secured or whether transmission is possible by spatial multiplexing using a multi-antenna technology.

An N-point DFT unit for performing discrete Fourier transform on parallel data for each divided frequency band;
A spectrum mapping unit for mapping the plurality of data output from the N-point DFT unit to the center frequency of each divided frequency band;
An M-point IFFT unit performing an inverse fast Fourier transform on the data output from the spectrum mapping unit; And
A filtering unit which filters inverse fast Fourier transformed data from the M-point IFFT unit;
Wireless data transmission device comprising a.

5. The method of claim 4,
The spectrum mapping unit,
Wireless spreading of the plurality of data output from the N-point DFT unit and spreading the plurality of spread data to each divided center frequency corresponding to each divided frequency band Device.

5. The method of claim 4,
The filtering unit is a wireless data transmission device, characterized in that for using a band pass filter (BPF).

5. The method of claim 4,
A P / S unit for converting parallel data output from the filtering unit into serial data; And
A DAC / RF unit converting digital data output from the P / S unit into analog data and transmitting the same through a selected channel;
Wireless data transmission device further comprising.

A filtering unit for filtering the received data when receiving data through a previously selected channel;
An M-point FFT unit performing fast Fourier transform on the data output from the filtering unit;
A spectral demapping unit for demapping data output from the M-point FFT unit at each divided center frequency corresponding to each divided frequency band; And
An N-point IDFT unit performing inverse discrete Fourier transform on the data output from the spectral inverse mapping unit;
Wireless data transmission device comprising a.

The method of claim 8,
The spectral inverse mapping unit,
And de-mapping data output from the M-point FFT unit at each divided center frequency corresponding to each divided frequency band, and despreading a plurality of de-mapped data.

The method of claim 8,
The filtering unit is a wireless data transmission device, characterized in that for using a band pass filter (BPF).

The method of claim 8,
An RF / ADC unit for converting analog data received through an antenna into digital data; And
An S / P unit converting the serial data converted into digital data into parallel data and outputting the parallel data to a filtering unit;
Wireless data transmission device further comprising.

Detecting unused resources available in a use band of an operating frequency band based on spectrum sensing technology;
Selecting a channel or frequency band for wireless data transmission based on the detected unused resources;
Determining whether communication can be started through the selected channel; And
When the communication is enabled, transmitting data through the selected channel;
Wireless data transmission method comprising a.

The method of claim 12,
Wherein the detecting comprises:
3. The wireless data transmission method of claim 1, wherein unused resources are detected according to the observation result by using three-dimensional observation of a use band of an operating frequency band based on the spectrum sensing technology.

The method of claim 12,
The determining step,
It is determined whether to start communication with a communication partner through a selected channel according to a predetermined criterion of whether communication can be started.
Here, the criterion for determining whether the communication can be started is one of whether a predetermined unused frequency band is secured or whether transmission is possible by spatial multiplexing using a multi-antenna technology.

The transmitting step,
Performing discrete Fourier transform on the parallel data for each divided frequency band;
Mapping the plurality of discrete Fourier transformed data to a center frequency of each divided frequency band;
Performing an inverse fast Fourier transform on the data mapped to the center frequency;
Filtering the inverse fast Fourier transformed data;
Converting the filtered parallel data into serial data; And
Converting the digital data converted into the serial data into analog data and transmitting the same through the channel;
Wireless data transmission method comprising a.

The method of claim 15,
The mapping step,
And spreading the plurality of discrete Fourier transform data, and mapping the spread spectrum data to each divided center frequency corresponding to each divided frequency band.