KR101393428B1 - Chip equalizer and equalizing method - Google Patents

Abstract

We present a chip equalizer and equalization method that minimizes complexity for signal demodulation and adaptively changes the amount of computation according to the performance of the receiver. The chip equalizer of the present invention includes a delay control module for recognizing an area containing a main signal from a signal distribution of a signal received from a tuner and determining a noise compensation area according to a delay difference between adjacent main signals; At least one first unit delay module delaying a signal of an area including a main signal among signals received through a tuner at chip unit intervals and outputting the delayed signal to a tap coefficient estimation module; And at least one second unit delay module for delaying, based on the control of the delay control module, a signal of an area not including the main signal among the signals received through the tuner by a chip unit. According to the present invention, the amount of computation for signal demodulation can be minimized, thereby minimizing the power consumption of the receiving system, optimizing the amount of computation, and further simplifying the structure of the receiving system.

Description

CHIP EQUALIZER AND EQUALIZING METHOD < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and more particularly, to a chip equalizer and an equalization method capable of minimizing complexity for signal demodulation and adaptively changing a calculation amount according to performance of a receiver.

In recent years, commercialization of digital broadcasting services has been expanding as user demands for high quality audio and video services have increased, and digital broadcasting can be classified into satellite broadcasting and terrestrial broadcasting.

For satellite digital broadcasting, the satellite base station receives broadcast data from each broadcasting station and transmits it to the satellite via an uplink transmission path in a designated band. The satellite amplifies and frequency-converts the signal received from the satellite base station, do.

Accordingly, the receiver located within the satellite broadcast service area receives the broadcast signal from the satellite and reproduces the broadcast. In order to solve the problem of signal attenuation due to shadowing or blocking due to buildings, shields, etc., a broadcast signal is relayed using a gap filler.

FIG. 1 is a diagram for explaining a concept of a general satellite broadcasting system.

1, a satellite broadcasting system includes a broadcasting station 100, a satellite base station 110, a satellite 120, a satellite control station 130, a broadcast receiving terminal 140, and a gap filler 150 .

The satellite base station 110 receives the broadcast data provided from each broadcasting station 100 and transmits the broadcast data to the satellite 120 through the uplink transmission path of the Ku band (12.5 GHz to 18 GHz). A plurality of broadcast stations 100 may transmit the broadcast data to the satellites 120 through one or more satellite base stations 110.

The satellite 120 amplifies the broadcast signal of the Ku band received from the satellite base station 110 and converts it into a broadcast signal of the S band. Then, the converted S-band broadcast signal is transmitted along with the Ku-band broadcast signal toward the service area.

The satellite control station 130 performs a function of monitoring and controlling the operation state of the satellite 120.

In the satellite broadcast service area, the broadcast receiving terminal 140 receives a broadcast signal from the satellite 120 and reproduces the broadcast.

However, at a point where signal attenuation is severe due to shadowing or blocking due to a building or a shield, the gap filler 150 relays and transmits the broadcast signal. The gap filler 150 receives a Ku-band TDM (Time Division Multiplexing) signal from the satellite 120 and converts it into an S-band CDM (Code Division Multiplexing) signal.

The broadcast receiving terminal 140 in the satellite broadcasting service area demodulates and reproduces the S-band CDM signal received from the satellite 120 and the S-band CDM signal received via the gap filler 150. [ The broadcast receiving terminal 140 may be a portable terminal (for example, a mobile communication terminal, a personal data assistant (PDA), a vehicle-mounted terminal), or the like.

2 is a diagram for explaining a frame structure of a baseband transmission signal of a general gap filler.

Referring to FIG. 2, the frame structure includes 12.75 ms as a basic frame. The six basic frames constitute a super frame of 76.5 ms. Each broadcast channel is a QPSK signal of 816 bytes (6528 bits), and consists of 408 bytes each of an I (In-Phase) channel and a Q (Quadrature-Phase) channel. A pilot channel assigned to a Walsh code 0 is used for transmission of frame synchronization and control data, and a pilot symbol (PS: pilot symbol) and a control data Di are configured in units of 25 us. One pilot channel frame is composed of 102 blocks composed of 32 bits (i.e., 125 占 퐏, 2048 chips). That is, one pilot channel frame is composed of 51 pilot symbols (PS) and control data Di (i = 1, 2, ..., 51). The first control data D1 of the pilot channel is a unique word for frame synchronization. The pilot symbols are transmitted in the order of "11111111 11111111 11111111 11111111", and the unique word D1 is transmitted in the order of "01101010 10110101 01011001 10001010". The pilot symbol PS and the unique word D1 are pilot data that the broadcast receiving terminal 140 already recognizes.

3 is a configuration diagram of a general satellite broadcast transmission system.

As shown in the figure, the satellite broadcast transmission system is a part for encoding an audio / video signal (AV signal), and includes Reed-Solomon (RS) encoders 110-1 to 111-n, a byte interleaver, A plurality of convolutional encoders 130-1 to 130-n, bit interleavers 140-1 to 140-n, and a part for encoding a pilot signal as a control signal A Reed Solomon (RS) encoder 110-x, a byte interleaver 120-x, a convolutional encoder 130x, a modulator 150 for modulating the encoded AV signal and pilot signal, a frequency up- And an up-converter 160 for transmitting the broadcast signal through the antenna.

In such a transmission system, broadcasting data is transmitted using different orthogonal spreading codes in order to enable independent broadcasting for each broadcasting station and / or contents. In the receiving system, Walsh codes are used for different broadcasting / Code.

4 is a configuration diagram of a general satellite broadcast receiving system.

The satellite broadcast receiving system includes tuners 210-1 to 210-2, a code division multiplex (CDM) demodulator 220, a channel demodulator 230, a demultiplexer 240, and a pilot channel demodulator 250 .

The CDM demodulation unit 220 includes a plurality of Rake fingers 2210-1 to 2210-2 and Rake fingers 2210-1 to 2210-2 for receiving a broadcast signal according to a PN code, The despreaders 2230-1 to 2230-2 that despread the output signals of the adders 2220-1 to 2220-2 and the adders 2220-1 to 2220-2 using Walsh codes are combined according to the signal strength and delay. 2, the output signal of the CDMA demodulation unit 220 is divided into a broadcast channel signal and a pilot channel signal. The broadcast channel signal is demodulated by the channel demodulator 230, the pilot channel signal is demodulated by the pilot channel demodulator 250, Respectively.

To this end, the channel demodulator 230 includes bit deinterleavers 2310-1 to 2310-1, Viterbi decoders 2320-1 to 2320-2, and byte deinterleavers 2330-1 to 2330-2 And a Reed Solomon (RS) demodulator 2340-1 to 2340-2. The pilot channel demodulator 250 includes a Viterbi decoder 2510, a byte deinterleaver 2520, a Reed Solomon decoder 250, Receiver controller 2540.

In addition, the signals reconstructed into the audio signal and the video signal in the channel demodulator 230 are demultiplexed and demodulated by the demultiplexer 240.

In the current satellite broadcast receiving system, the Walsh code orthogonality of the received signal is lost due to the delay and frequency spread of the received signal in the multipath channel environment, so that multi-channel interference may occur. In this case, There is a problem. This problem can be solved by a method of reducing an interference signal, but in this case, a broadcasting service channel is limited.

Therefore, a method for minimizing the interference between received signals without limiting the broadcast channel has been studied. One solution is to introduce an equalizer in the receiving system.

The equalization is a signal processing technique that removes channel noise and channel distortion due to signal delay caused by multipath, and has characteristics of uniform amplitude and phase over the entire frequency band. In general, the equalizer compensates for intersymbol interference by adjusting the tap coefficients according to the delay characteristics of the input signal using a fixed tap line with a tap. The tap coefficient may be changed according to the channel estimation information and may be determined according to noise signals, i.e., delay signals, distributed in delay positions around the data signals. In other words, the tap coefficient is set to a value for removing the noise signal.

5 is a diagram for explaining a receiving system using a general chip equalizer.

The chip equalizer 300 includes a first equalizer 302 that obtains channel information using a pilot channel signal recognized from a broadcast signal received through a tuner, and updates tap coefficients by using the obtained channel information, A second equalizer 302 for generating a recovered pilot signal according to the tap coefficient updated by the first equalizer 302 and then performing a second update of the tap coefficient using the recovered pilot signal and the pilot channel signal recognized from the received broadcast signal, And a detector 306 that restores the received broadcast signal using the tap coefficients updated by the second equalizer 304 and the second equalizer 304 and transmits the restored broadcast signal to the channel demodulator.

The tap coefficient updating process in the chip equalizer 300 will be described with reference to FIG.

6 is a detailed configuration diagram of the equalizer shown in Fig.

As shown in the figure, the equalizer includes a unit delay module 312 for delaying broadcast signals received through a tuner at chip unit intervals, a spreading code for each signal output from each output terminal of the unit delay module 312, A tap coefficient estimating module 314 for calculating the recovered pilot signal by summing up the results of applying the code and outputting the updated tap coefficient by applying the currently set tap coefficient and an output signal of the tap coefficient estimating module 314, The step size is updated using the error value calculated by the adder 316 and the adder 316 that calculates an error value from the pilot channel signal recognized from the broadcast signal, And a step size adjustment module 318 for updating the tap coefficients.

In this equalizer structure, the unit delay module forms a 64-bit block by moving a received bit signal, for example, a combination of a Walsh code and a PN code sequence used for a common pilot corresponding to 64 chips, The sum of the blocks is one bit unit.

An example of such an equalizer is disclosed in Korean Patent Laid-Open Publication No. 2006-39961.

When the equalizer is applied to the receiving system, the multipath channel tracking is possible and interference between adjacent channels can be minimized. However, since all the noise signals included in the received signal must be compensated by applying tap coefficients, There is an increased disadvantage.

In particular, since a mobile communication terminal for using a satellite broadcasting service has poor performance as compared with a device such as a base station, there is a problem that the complexity increases and the operation speed decreases when a chip equalizer such as the one described above is applied.

Technical Challenge

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems and disadvantages, and it is an object of the present invention to provide a chip equalizing method capable of improving the performance of a receiving system using an equalizer and compensating for a noise signal only for a portion including a main signal component, And an equalization method.

Another object of the present invention is to adaptively change the amount of calculation for noise signal compensation according to the performance of the receiving system, thereby changing the performance of the receiving system according to the purpose.

Technical Solution

According to an aspect of the present invention, there is provided a chip equalizer that recognizes a region including a main signal from a signal distribution of a signal received from a tuner, A delay control module for determining a delay time; At least one first unit delay module delaying a signal in an area including a main signal among the signals received through the tuner at chip unit intervals and outputting the delayed signal to a tap coefficient estimation module; And at least one second unit delay module for delaying, in units of chips, a signal of an area not including a main signal among the signals received through the tuner under the control of the delay control module.

Also, a chip equalizer according to another embodiment of the present invention recognizes a region including a main signal from a signal distribution of a signal received from a tuner, identifies a range of an area containing the main signal, A delay control module for determining a noise compensation area and a range according to a delay difference; A delay unit for delaying signals in a frequency range including the main signal among the signals received through the tuner in units of chip units under control of the delay control module and outputting the delayed signals to at least one first unit delay module; And at least one second unit delay module for delaying, in units of chips, a signal of an area not including a main signal among the signals received through the tuner under the control of the delay control module.

In addition, the equalization method according to an embodiment of the present invention analyzes a profile of a received signal by receiving a signal through a tuner, recognizes a region containing a main signal, and determines a window position (i.e., a noise compensation region) ; A second step of estimating a tap coefficient for an area including the main signal according to the window position; A third step of calculating an error value with reference to the tap coefficient estimated in the second step and the pilot channel signal recognized from the received signal; A fourth step of updating the step size according to the error value; And a fifth step of updating the estimated tap coefficient according to the updated step size.

Advantageous effect

According to the present invention, in a receiving system using an equalizer, power consumption of a receiving system can be minimized and calculation amount can be optimized by minimizing a calculation amount for signal demodulation, and further, there is an advantage that a structure of a receiving system can be simplified.

In addition, the amount of computation for noise compensation can be adaptively changed according to the performance of the receiving system, and the performance of the receiving system can be changed according to the application. In a small receiving system requiring less processing power, Various broadcast signals can be received and reproduced.

1 is a diagram for explaining a concept of a general satellite broadcasting system;

2 is a diagram for explaining a frame structure of a baseband transmission signal of a general gap filler.

3 is a configuration diagram of a general satellite broadcast transmission system,

4 is a configuration diagram of a general satellite broadcast receiving system,

5 is a diagram for explaining a receiving system using a general chip equalizer,

FIG. 6 is a detailed configuration diagram of the equalizer shown in FIG. 5,

7 is a configuration diagram of a chip equalizer according to an embodiment of the present invention,

8 is a configuration diagram of a chip equalizer according to another embodiment of the present invention,

9 is a flowchart for explaining an equalization method according to the present invention.

Description of the Related Art [0002]

302: first equalizer 304: second equalizer

306: Detector 320: Chip equalizer

3210: delay control module 3220, 3240: first unit delay module

3230: second unit delay unit 3250: tap coefficient estimation module

3260: adder 3270: step size adjustment module

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described more specifically with reference to the accompanying drawings.

7 is a configuration diagram of a chip equalizer according to an embodiment of the present invention.

The chip equalizer 320 according to an exemplary embodiment of the present invention analyzes a profile of a signal received from a tuner and recognizes a region including a main signal and a region not including a main signal from a distribution of a received signal, A delay control module 3210 for determining a noise compensation region according to the difference, at least one first unit delay module 3220, 3240 for delaying signals in an area including a main signal among the signals received through the tuner, And at least one second unit delay module 3230 for delaying, in units of chips, a signal of an area not including the main signal among the signals received through the tuner.

The delay control module 3210 determines a region including a main signal among the received signals as a noise compensation region and transmits a signal of an area including the main signal to the first unit delay modules 3220 and 3240. Also, the delay control module 3210 transmits a signal of an area not including a main signal among the reception signals to the second unit delay module 3230.

The tap coefficient estimating module 3250 receives the signals output from the respective output terminals of the first unit delay modules 3220 and 3240 and applies a spreading code to each of the output signals, Calculates the recovered pilot signal, and outputs the updated tap coefficient by applying the currently set tap coefficient.

The adder 3260 calculates an error value from the output signal of the tap coefficient estimating module 3250 and the pilot channel signal recognized from the received broadcast signal and the step size adjusting module 3270 calculates the error value from the pilot channel signal obtained from the adder 3260 Updates the step size using the error value, and transmits the step size update result to the tap coefficient estimation module 3250 to update the tap coefficient. Here, the step size adjustment module 3270 may be implemented by an adaptive LMS (Least Mean Square) method.

In this embodiment, the main signals included in the received signal do not all exist over a wide area, but attention is paid to channel characteristics appearing in a burst form in a state in which there is a delay difference, And compensates for noises in the other areas. Thus, it is possible to minimize the amount of calculation required for restoring the received signal in a receiving system having a limited signal processing capacity like a mobile communication terminal.

8 is a configuration diagram of a chip equalizer according to another embodiment of the present invention.

The present embodiment shows a chip equalizer capable of controlling the noise compensation range of a region including a main signal component in addition to the structure of the chip equalizer described in Fig.

That is, the chip equalizer 330 according to the present embodiment recognizes a region including a main signal and a region not including a main signal from a signal distribution of a signal received from the tuner, confirms a range of a region including the main signal, A delay control module 3310 for determining a noise compensation region and a range according to a delay difference between main signals that are included in the main signal received through the tuner 3310, At least one first unit delay module (3320, 3340) for delaying the first unit delay module (3320, 3340) at intervals of chip unit, at least one second unit And a delay module 3330.

The signals output from the respective output terminals of the at least one first unit delay module 3220 and 3240 are input to the tap coefficient estimation module 3350 and the tap coefficient estimation module 3350, the adder 3360, The module 3370 performs a function similar to that described with reference to FIG. 7, so a detailed description thereof will be omitted.

The chip equalizer 320 according to an embodiment of the present invention illustrated in FIG. 7 compensates for noise in a frequency range including a main signal by the same window (tap coefficient estimation window) size, The chip equalizer is further adapted to vary the window size of the signals for noise compensation according to the received signal characteristics.

In this embodiment, the window size is the size of the first unit delay modules 3220 and 3240 surrounded by a dotted line in FIG. 8, and is a size of a chip for outputting a delay signal to the tap coefficient estimation module 3350, Means the number of delay units Tc.

A method of estimating a tap coefficient according to a received signal input to the chip equalizer shown in FIGS. 7 and 8 and restoring the original signal using the tap coefficient will be described below.

9 is a flowchart for explaining an equalization method according to the present invention.

As the signal is received through the tuner, the delay control modules 3210 and 3310 analyze the profile of the received signal (S10), recognize the region containing the main signal and the region not including the main signal, The noise compensation area, i.e., the window position is determined (S20). Here, the delay control modules 3210 and 3310 may analyze the profile of the received signal and recognize that the received signal has a magnitude greater than a predetermined value as a main signal.

The received signals are delayed in units of chips in the first unit delay modules 3220, 3240, 3320, and 3340 according to the window positions determined in step S20, and input to the tap coefficient estimation modules 3250 and 3350 to perform tap coefficient estimation (S30). In step S30, the tap coefficient estimation modules 3250 and 3350 apply a spreading code to each output signal to calculate a recovered pilot signal by summing up the spreading code application results, And outputs the updated tap coefficient.

Thereafter, when an error value is calculated from the output signals of the tap coefficient estimation modules 3250 and 3350 and the pilot channel signal recognized in step S40, it is input to the step size adjustment modules 3270 and 3370, When it is updated, it is input to the tap coefficient estimation modules 3250 and 3350 and the tap coefficients are updated (S60).

In addition to determining the noise compensation region according to the delay difference between adjacent main signals in the delay control modules 3210 and 3310 after performing Step S20 and before performing Step S30, The size determination step S25 may be further performed. In this case, since the noise compensation range can be adaptively changed, there is an advantage that the amount of calculation for signal demodulation can be minimized.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

According to the present invention, in a receiving system using an equalizer, power consumption of a receiving system can be minimized and calculation amount can be optimized by minimizing a calculation amount for signal demodulation, and further, there is an advantage that a structure of a receiving system can be simplified.

In addition, the amount of computation for noise compensation can be adaptively changed according to the performance of the receiving system, and the performance of the receiving system can be changed according to the application. In a small receiving system requiring less processing power, Various broadcast signals can be received and reproduced.

Claims (14)

A chip equalizer for a receiving system, A delay control module for recognizing an area containing a main signal from a signal distribution of a signal received from the tuner and determining a noise compensation area according to a delay difference between adjacent main signals; At least one first unit delay module delaying a signal in an area including a main signal among the signals received through the tuner at chip unit intervals and outputting the delayed signal to a tap coefficient estimation module; And And at least one second unit delay module for delaying, in a chip unit, signals in an area not including a main signal among signals received through the tuner under the control of the delay control module. The method according to claim 1, Wherein the chip equalizer applies a spreading code to the signals output from the respective output terminals of the at least one first unit delay module, calculates a recovered pilot signal by summing all the spreading code application results, A tap coefficient estimating module for applying the updated tap coefficient; An adder for calculating an error value with reference to an output signal of the tap coefficient estimating module and a pilot channel signal recognized from a signal received from the tuner; And And a step size adjustment module for updating the step size using the error value calculated by the adder and transmitting the step size update result to the tap coefficient estimation module. 2. The chip equalizer of claim 1, wherein the delay control module analyzes a profile of a received signal and recognizes an area including a main signal among the received signals. The chip equalizer of claim 3, wherein the delay control module recognizes that a signal having a magnitude equal to or greater than a predetermined value in the received signal is a main signal. The delay control module according to claim 1, wherein the delay control module transmits a signal in an area including a main signal among the received signals to the first unit delay module, Wherein the unit delay module transmits the signal to the unit delay module. A chip equalizer for a receiving system, Recognizes an area including the main signal from the signal distribution of the signal received from the tuner, confirms the range of the area containing the main signal, determines the noise compensation area and the noise compensation range according to the delay difference between adjacent main signals A delay control module; A first delay unit for delaying signals in an area including the main signal among the signals received through the tuner in units of chip units under control of the delay control module and outputting the signals to the tap coefficient estimation module, module; And And at least one second unit delay module for delaying, in a chip unit, signals in an area not including a main signal among signals received through the tuner under the control of the delay control module. The method according to claim 6, Wherein the chip equalizer applies a spreading code to the signals output from the respective output terminals of the at least one first unit delay module, calculates a recovered pilot signal by summing all the spreading code application results, A tap coefficient estimating module for applying the updated tap coefficient; An adder for calculating an error value with reference to an output signal of the tap coefficient estimating module and a pilot channel signal recognized from a signal received from the tuner; And And a step size adjustment module for updating the step size using the error value calculated by the adder and transmitting the step size update result to the tap coefficient estimation module. 7. The chip equalizer of claim 6, wherein the delay control module analyzes the profile of the received signal and recognizes an area including a main signal among the received signals. 9. The chip equalizer of claim 8, wherein the delay control module recognizes that a signal having a magnitude equal to or greater than a predetermined value in the received signal is a main signal. The chip equalizer of claim 6, wherein the noise compensation range is a number of chip delay units in the first unit delay module outputting a signal delayed by chip unit interval to a tap coefficient estimating module. The delay control module according to claim 6, wherein the delay control module transmits a signal in an area including a main signal among the received signals to the first unit delay module, Wherein the unit delay module transmits the signal to the unit delay module. An equalization method in a receiving system, A signal is received through a tuner to analyze a profile of a received signal to recognize a region including a main signal and a region not including the main signal and to perform a noise compensation according to a delay difference between adjacent main signals in the region including the main signal A first step of determining a window position for a region; A second step of estimating a tap coefficient for an area including the main signal according to the determined window position; A third step of calculating an error value with reference to the tap coefficient estimated in the second step and the pilot channel signal recognized from the received signal; A fourth step of updating the step size according to the error value; And And a fifth step of updating the estimated tap coefficient according to the updated step size. 13. The equalizing method of claim 12, wherein, in the first step, a signal having a magnitude equal to or greater than a predetermined value is recognized as a main signal. 13. The method of claim 12, Further comprising the step of determining a noise compensation range for a region in which the main signal is located before performing the second step after performing the first step.

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