JP2008035171A - Radio communication apparatus and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus and system capable of improving a communication quality even if an intersymbol interference by a multipulse generates. <P>SOLUTION: The radio communication apparatus 100 at a transmission side transmits a known symbol row whose code decision object symbol is "1" and the known symbol row whose code decision object symbol is "0" to each pattern which a symbol for an interference generating estimation term can get in a transmission frame. The radio communication apparatus 100 at a receiving side sets a data apportioner 130 to sort the known symbol rows according to the patterns, a threshold detector 135 to generate a first code decision threshold from the known symbol row having a first pattern, a threshold detector 136 to generate a second code decision threshold, and a code judging portion 125 to conduct a code decision of a receiving signal by using a threshold set including the first code decision threshold and the second threshold and to output decision results as a demodulation data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In particular, the present invention relates to a radio communication apparatus and a radio communication system that improve communication quality even when intersymbol interference occurs due to multipath.

  As a conventional ASK demodulation method, two types of threshold values corresponding to received waveform distortion due to filter characteristics of a wireless communication system are prepared, and the threshold value used for code determination is switched according to the code of demodulated data one symbol before An ASK demodulation method is known. The reception data specifying means (demodulation means) using this conventional ASK demodulation method is disclosed in Patent Document 1, and its configuration is shown in FIG. FIG. 12 is a diagram for explaining the ASK demodulation method in the received data specifying means. In FIG. 12, an analog demodulated waveform whose band is limited after detection is shown in the upper stage, and a digital demodulated waveform is shown in the lower stage.

  The received data specifying means (demodulation means) 10 in FIG. 11 inputs an analog demodulated waveform as shown in the upper part of FIG. 12, determines the sign by the comparing means 11, and outputs the digital demodulated waveform shown in the lower part of FIG. 12. .

  In the received data specifying means (demodulating means) 10, the digital demodulated signal is delayed by one symbol period by the filters 12 a and b and the comparators 13 a and b, converted into a predetermined amplitude by the amplitude adjusting means 14, and the voltage source 15 By being offset, a threshold waveform indicated by the wavy line in the upper part of FIG. 12 is formed. The comparison means 11 determines the sign of the next symbol using this threshold value.

By generating a threshold value used for code determination of the current symbol from the demodulated signal one symbol before, for example, it corresponds to the amplitude of the code “1” after the code “0” that has become smaller due to waveform distortion due to the filter characteristics. Thus, the threshold value used for the code determination of the symbol following the code “0” can be set smaller than the normal value, and the demodulation performance can be improved.
JP 2005-223387 A

  By the way, when a high-speed wireless transmission exceeding 1 Gsps is used in an indoor multipath environment, if a delayed wave having a propagation distance difference of 30 cm is generated, this delayed wave becomes a delayed wave of 1 ns or more, which is one symbol period. Cause interference. In the case of using an ASK modulated wave demodulation method in such an environment, a code determination method using a threshold corresponding to waveform distortion caused by intersymbol interference is considered to be effective.

  However, in the demodulating means based on the conventional ASK demodulation method, the known waveform distortion caused by the filter characteristics is considered, but the waveform distortion caused by intersymbol interference due to multipath is not considered at all. Therefore, for example, when a waveform distortion in which the amplitude of the subsequent code increases due to the influence of the delayed wave of the code “1”, the probability of erroneously setting the code “0” as the code “1” increases, and so on. May not be obtained and communication quality may be reduced.

  The present invention has been made in view of this point, and can perform demodulation while suppressing a decrease in error rate and the like even when intersymbol interference due to multipath occurs, thereby improving communication quality. An object is to provide a wireless communication device and a wireless communication system.

  The wireless communication apparatus according to the present invention generates a first code determination threshold value from the known data having a first pattern and a data distribution unit that distributes known data in consideration of a delayed wave according to the pattern of the known data First threshold value generating means, second threshold value generating means for generating a second code determination threshold value from the known data having a second pattern, and the first code determination threshold value. And a demodulating unit that performs code determination of a received signal using a threshold set including a value and the second code determination threshold, and outputs a code determination result as demodulated data.

  The wireless communication system of the present invention includes a wireless transmission device that transmits a wireless frame having a threshold generation period including all combinations of code sequences having a length corresponding to a delay time due to multipath, and the threshold generation period Is generated by a data distribution unit that distributes a code string included in the pattern according to a pattern, a threshold generation unit that generates a code determination threshold corresponding to known data of each pattern, and the threshold generation unit A configuration is provided that includes a radio receiving apparatus that includes a demodulating unit that performs code determination of a received signal using a set of code determination threshold values and outputs a code determination result as demodulated data.

  According to the present invention, it is possible to provide a radio communication apparatus and a radio communication system capable of performing demodulation while suppressing a decrease in error rate and the like and improving communication quality even when intersymbol interference due to multipath occurs. can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment, the same components are denoted by the same reference numerals, and the description thereof will be omitted because it is duplicated.

(Embodiment 1)
FIG. 1 is a block diagram of a radio communication system according to Embodiment 1 of the present invention. As shown in the figure, the wireless communication system includes wireless communication devices 100a and 100b using ASK modulation. In this wireless communication system, a microwave or millimeter wave band is mainly used. Assuming that the wireless communication device 100a performs ASK modulation on transmission data and transmits a transmission frame, and the wireless communication device 100b receives and ASK-demodulates this transmission frame, the wireless communication device 100a performs the following in the preamble period in the transmission frame: Transmit including “known symbol sequence”.

  Here, the “known symbol sequence” has a length corresponding to the multipath delay time in an environment where the wireless communication system is used. Further, the known symbol string is composed of “symbols subject to code determination” and symbols of “inter-symbol interference expected period (hereinafter referred to as“ interference occurrence expected period ”)” that precedes (that is, the transmission order precedes). Become.

  The wireless communication device 100b obtains a threshold value according to the pattern of the known symbol sequence included in the received frame, and sequentially switches to the threshold value obtained from the known symbol sequence according to the symbol pattern of the data portion to be demodulated. Demodulate.

  That is, radio communication apparatus 100a has a known symbol string whose code determination target symbol is “1” and a code determination target symbol of “0” for each pattern that can be taken by a symbol in the expected occurrence period of interference in the transmission frame. And the known symbol sequence that is “”. The wireless transmission device 100b knows in advance the position of each known symbol sequence in the frame, and the power value of the code determination target symbol in the known symbol sequence having the same symbol pattern in the expected occurrence period of interference and different code determination target symbols Based on the above, a threshold value is generated for each symbol pattern in the expected interference occurrence period. Radio transmitting apparatus 100b performs code determination of the current symbol using a threshold value obtained from the symbol pattern of the expected period of occurrence of interference having the same pattern as the symbol pattern that has already been subjected to code determination.

  Next, the configuration of the wireless communication apparatus 100 will be described.

  The wireless communication apparatus 100 includes an antenna 110, a transmission / reception unit 111, and a control unit 112.

  The transmission / reception unit 111 transmits a high-frequency signal obtained by ASK-modulating the transmission data S116 from the control unit 112 via the antenna 110. In addition, the transmission / reception unit 111 performs code determination on the high-frequency signal received via the antenna 110 as “1” or “0”, and outputs the code determination result to the control unit 112 as demodulated data S117.

  The transmission / reception unit 111 includes an antenna duplexer 113, a transmission unit 114, and a reception unit 115. The antenna duplexer 113 performs an antenna switching operation in the transmission / reception operation. The transmission unit 114 performs a transmission operation by ASK modulation. The antenna duplexer 113, the transmission unit 114, and the reception unit 115 are controlled by a control signal from the control unit 112.

  The receiving unit 115 performs an ASK modulated wave reception operation. Specifically, the reception unit 115 includes a detection unit 118, a sampling unit 120, and a demodulation unit 122.

  The detection unit 118 detects the received high-frequency signal after band limitation and outputs a detection signal S119 to the sampling unit 120. The sampling unit 120 samples the baseband signal obtained by limiting the band of the detection signal S119 at a predetermined timing and outputs the sampling data S121 to the demodulation unit 122.

  The demodulator 122 determines the code of the sampling data S121 and generates demodulated data S117. Specifically, the demodulation unit 122 includes a threshold value generation unit 123, a threshold value switching unit 124, and a code determination unit 125.

  The threshold generator 123 uses the sampling data S121 to generate an appropriate threshold set in consideration of intersymbol interference. That is, the threshold generation unit 123 distributes the sampling data S121 for each pattern of the known symbol sequence included in the preamble period of the received frame, and has the same symbol pattern in the expected period of occurrence of interference and has different known symbols for code determination. Based on the power value of the code determination target symbol in the symbol string, a threshold value is generated for each symbol pattern in the expected interference occurrence period.

  Specifically, as shown in FIG. 2, the threshold value generation unit 123 includes a data distribution unit 130, a minimum value detection unit 131, a maximum value detection unit 132, a minimum value detection unit 133, and a maximum value detection unit. 134, a threshold detection unit 135, and a threshold detection unit 136.

  The data distribution unit 130 distributes the sampling data S121 corresponding to the data with a known symbol pattern included in the preamble period 140 of the communication frame having the format shown in FIG. 3 for each symbol pattern. Here, the sampling data S121 corresponding to the known data whose pattern of the known symbol sequence is “11”, that is, the symbol of the interference occurrence expectation period is “1” and the code determination target symbol is “1” is the minimum value detection unit. It is output to 131. Further, when the known symbol string is “10”, it is output to the maximum value detector 132, and when the known symbol string is “01”, it is output to the minimum value detector 133, and the known symbol string is “00”. "Is output to the maximum value detector 134.

  The minimum value detection unit 131 evaluates the minimum value of the sampling data S121 column of the code “1” following the code “1” distributed by the data distribution unit 130. That is, the minimum value detecting unit 131 detects the power value of the code determination target symbol “1” following the symbol “1” in the expected period of occurrence of interference. Here, since it is assumed that a plurality of known data having a known symbol string having the same pattern is included in a frame and sampling data S121 corresponding to the plurality of known data is evaluated, the minimum power among the power values is assumed. Detect value.

  The maximum value detection unit 132 evaluates the maximum value of the sampling data string S121 of the code “0” following the code “1” distributed by the data distribution unit 130.

  The minimum value detection unit 133 evaluates the minimum value of the sampling data string S121 of the code “1” following the code “0” distributed by the data distribution unit 130.

  The maximum value detection unit 134 evaluates the maximum value of the sampling data string S121 of the code “0” following the code “0” distributed by the data distribution unit 130.

  FIG. 4 is an analysis example of a baseband signal obtained by band-limiting the detection signal S119. 4, (a) is an example of signal analysis for all codes, (b) is an example of analysis of a baseband signal corresponding to a symbol following the code “1”, and (c) is an example of code “0”. Is an analysis example of a baseband signal corresponding to a symbol following "." As shown in FIG. 4A, the input signal of the threshold value generation unit 123 includes sampling data of known symbol sequences of all patterns, and the data distribution unit 130 distributes each pattern of known symbol sequences. It is done. The minimum value detecting unit 131 detects the minimum power value at the sampling timing among the bundle of curves appearing on the upper side of FIG. 4B, and the maximum value detecting unit 132 detects the bundle of lower curves. Among these, the maximum power value is detected at the sampling timing.

  The threshold detection unit 135 generates a first threshold S137 from an intermediate value between the output of the first minimum value detection unit 131 and the output of the first maximum value detection unit 132. The threshold detection unit 135 sets the power value of the code determination target symbol “1” following the symbol “1” in the expected interference occurrence period and the code determination target symbol “0” following the symbol “1” in the expected interference occurrence period. An intermediate value with respect to the power value is obtained, and the intermediate value is set as a threshold value when the symbol pattern in the expected period of occurrence of interference is “1”.

  Specifically, the minimum power value is detected at the sampling timing among the bundle of curves appearing on the upper side of FIG. 4B, and the maximum power value at the sampling timing is detected among the bundle of lower curves. From these power values, a first threshold value S137, that is, a threshold value when the symbol pattern in the expected period of occurrence of interference is “1” is generated.

  In this way, in order to determine whether the code determination target symbol is “1” or “0” in consideration of the effect of inter-symbol interference on the code determination target symbol based on the symbol pattern in the expected interference occurrence period. A suitable threshold can be determined. In particular, since the power value in the case of the code determination target symbol “1” is large and the power value in the case of the code determination target symbol “0” is small, the difference between the two power values is the smallest and the code determination is most difficult. The threshold value obtained at this time becomes the optimum threshold value for the symbol pattern in each interference expected period. Therefore, here, an intermediate value between the minimum power value of the code determination target symbol “1” and the maximum power value of the code determination target symbol “0” is generated as the threshold value S137.

  The threshold detection unit 136 generates a second threshold S138 from an intermediate value between the output of the second minimum value detection unit 133 and the output of the second maximum value detection unit 134. From FIG. 4C, the first threshold value S138, that is, the threshold value when the symbol pattern in the expected interference occurrence period is “0” is generated. The first threshold value S137 and the second threshold value S138 generated by the threshold value detection unit 135 and the threshold value detection unit 136 are “threshold value sets”.

  Returning to FIG. 1, the threshold value switching unit 124 selects an optimum threshold value from the “threshold value set” in accordance with the sign of the previous demodulated data S117. That is, the threshold value switching unit 124 receives the demodulated data S117, which is the code determination result of the code determining unit 125, and is obtained with respect to the symbol pattern in the expected period of occurrence of interference that matches the pattern of the latest demodulated data S117. Select the threshold from “Threshold Set”. The selected threshold value is output to the code determination unit 125.

  The code determination unit 125 performs code determination of the sampling data S121 using the threshold selected by the threshold switching unit 124, and outputs the determination result as demodulated data S117. In this way, the threshold value switching unit 124 sequentially switches to the threshold value obtained from the symbol pattern in the expected period of occurrence of interference having the same pattern as the symbol pattern that has already been subjected to code determination, and the code determination unit 125 Performs the sign determination of the current symbol.

  FIG. 5 is a flowchart of the demodulation operation in the demodulator 122. Hereinafter, the demodulation operation of the wireless communication apparatus 100 will be described with reference to FIGS. 1 to 5.

  In step 1001, the sampling data S121 of the preamble period 140 of the received signal is divided according to the code sequence “11”, “10”, “01”, “00” by the data allocating unit 130. Are assigned to the minimum value detection unit 131, the first maximum value detection unit 132, the second minimum value detection unit 133, and the second maximum value detection unit 134.

  In step 1002, the maximum value or the minimum value of the sampling data S121 to which each of the detection units 131 to 134 is distributed is evaluated. Specifically, the first minimum value detection unit 131 evaluates the minimum value of the code “1” following the code “1”. The first maximum value detector 132 evaluates the maximum value of the code “0” following the code “1”. In the second minimum value detection unit 133, the minimum value of the code “1” following the code “0” is evaluated. In the second maximum value detection unit 134, the maximum value of the code “0” following the code “0” is evaluated.

  In step 1003, threshold values are obtained by threshold value detectors 135 and 136. Specifically, in the first threshold value detection unit 135, the average of the output of the first minimum value detection unit 131 and the output of the first maximum value detection unit 132 is taken, thereby FIG. The optimum value for sign determination in the eye pattern is obtained, and this optimum value is output as the first threshold value S137. Further, the second threshold value detection unit 136 takes the average of the output of the second minimum value detection unit 133 and the output of the second maximum value detection unit 134, so that the eye pattern of FIG. The optimum value of the code determination at is obtained, and this optimum value is output as the second threshold value S138. The first threshold value S137 and the second threshold value S138 are a “threshold set”.

  In step 1004, in the data period 141 of the received signal, the threshold value switching unit 124 determines whether the previous demodulated data S117 is “1” or “0”. That is, the threshold value switching unit 124 identifies the symbol pattern of the expected interference occurrence period corresponding to the latest demodulated data S117.

  If the result of this determination is that the code is “1”, then in step 1005, the first threshold value S137 is selected from the threshold value set, and the first threshold value S137 is used for the code determination. Output as a value.

  As a result of the determination, if the code is “0”, in step 1006, the second threshold value S138 is selected from the threshold value set, and is output as the threshold value used for the code determination.

  Thus, in steps 1004 to 1006, the threshold value obtained in step 1003 for the symbol pattern in the expected interference occurrence period corresponding to the pattern of the latest demodulated data S117 is selected from the threshold set.

  In step 1007, the code determination unit 125 performs code determination on the sampling data S121 using the threshold value output from the threshold value switching unit 124, and outputs the determination result as demodulated data S117.

  With the above operation, received data transformed as shown in FIG. 4A due to inter-symbol interference due to multipath is classified as shown in FIGS. 4B and 4C, and the optimum threshold value is used for each. The code can be determined, and the demodulation performance in a multipath environment can be improved.

  In the above description, the case of 1-bit intersymbol interference, that is, intersymbol interference between adjacent symbols has been described. However, even the intersymbol interference when the delay is 2 bits or more can be processed similarly. Demodulation in a communication state in which intersymbol interference occurs in multiple bits by performing code determination using a threshold set corresponding to the number of bits required in the same procedure (number of symbols in the expected interference occurrence period) The performance can be improved. As an example, a radio communication apparatus that can cope with the occurrence of 1- or 2-bit intersymbol interference will be described with reference to FIG.

  As illustrated in FIG. 6, the wireless communication device 100 includes a demodulation unit 300, and the demodulation unit 300 includes a threshold value generation unit 301 and a threshold value switching unit 319. The threshold generation unit 301 includes a data distribution unit 302, a first minimum value detection unit 303, a first maximum value detection unit 304, a second minimum value detection unit 305, and a second maximum value. The detection unit 306, the third minimum value detection unit 307, the third maximum value detection unit 308, the fourth minimum value detection unit 309, the fourth maximum value detection unit 310, and the first threshold It has a value detector 311, a second threshold detector 312, a third threshold detector 313, and a fourth threshold detector 314.

  The data distribution unit 302 distributes the sampling data S121 corresponding to the data with a known symbol pattern included in the preamble period 140 for each symbol pattern. Here, the sampling data S121 of the code “1” following the code sequence “11”, in other words, the sampling corresponding to the known data in which the symbol of the expected interference occurrence period is “11” and the code determination target symbol is “1”. The data S121 is output to the first minimum value detection unit 303. When the known symbol sequence is “110”, it is output to the first maximum value detection unit 304, and when the known symbol sequence is “101”, it is output to the second minimum value detection unit 305. When the known symbol string is “100”, it is output to the second maximum value detector 306. Further, when the known symbol sequence is “011”, it is output to the third minimum value detector 307, and when the known symbol sequence is “010”, it is output to the third maximum value detector 308. When the known symbol string is “001”, it is output to the fourth minimum value detector 309, and when the known symbol string is “000”, it is output to the fourth maximum value detector 310.

  The first threshold value detector 311 detects the first threshold value S315 from the intermediate value between the output of the first minimum value detector 303 and the output of the first maximum value detector 304. The second threshold value detection unit 312 detects the second threshold value S316 from the intermediate value between the output of the second minimum value detection unit 305 and the output of the second maximum value detection unit 306. The third threshold value detection unit 313 detects the third threshold value S317 from the intermediate value between the output of the third minimum value detection unit 307 and the output of the third maximum value detection unit 308. The fourth threshold value detection unit 314 detects the fourth threshold value S318 from the intermediate value between the output of the fourth minimum value detection unit 309 and the output of the fourth maximum value detection unit 310.

  The first threshold value S315, the second threshold value S316, the third threshold value S317, and the fourth threshold value S318 constitute a “threshold value set” here. Here, since it is assumed that the inter-symbol interference of 2 bits, that is, the number of symbols in the expected period of occurrence of interference is 2, four threshold values which are the number of possible combinations of 2 bits are "Threshold set".

  The threshold value switching unit 319 selects and outputs the first threshold value S315 from the “threshold value set” when the immediately preceding code arrangement, that is, the symbol pattern of the expected occurrence period of interference is “11”. , “10” selects the second threshold value S316, “01” selects the third threshold value S317, and “00” selects the fourth threshold value S318. Output.

  The code determination unit 125 performs code determination on the sampling data S121 using the threshold value received from the threshold value switching unit 319 according to the immediately preceding code determination result, and outputs it as demodulated data S117. In this way, it is possible to improve demodulation performance in a multipath environment in which waveform distortion due to 2-bit intersymbol interference occurs. Further, demodulation considering intersymbol interference over a plurality of symbols is possible, and multipath resistance is improved.

  In the above description, in FIGS. 2 and 6, the threshold value is detected including the noise state by obtaining the threshold value from the maximum value / minimum value in the preamble period. In order to place importance on the waveform distortion due to the above, a threshold value in which the influence of noise is reduced by using the average value of the maximum value / minimum value in a plurality of symbols for threshold detection may be used.

  In the above description, the case where threshold detection is performed using data with a known symbol pattern included in the preamble period has been described. In particular, the period for detecting the threshold is not limited to the preamble. The period is not limited. By providing a threshold generation period for threshold detection in the frame format, efficient threshold generation is possible. That is, by preparing a threshold detection period including code sequences “11”, “10”, “01”, “00”, it is possible to efficiently generate a threshold corresponding to 1-bit intersymbol interference. Can be done automatically. Furthermore, by preparing a threshold detection period including code sequences “111”, “110”, “101”, “100”, “011”, “010”, “001”, “000”, A threshold value corresponding to 2-bit intersymbol interference can be efficiently generated.

  Further, in the above description, the case where binary ASK is applied has been described, but the demodulation performance can be improved by generating a threshold set in the same procedure for multilevel ASK. Is possible.

  In addition, although the example of analysis of the received signal waveform by the RZ code is shown in FIG. 4 above, the present invention is not limited to this, and an NRZ code may be used.

  As described above, a threshold set corresponding to intersymbol interference is generated using a symbol with a known preamble code, and an appropriate threshold is selected from the threshold set according to the immediately preceding code sequence (demodulated data). By performing the code determination, it is possible to improve the demodulation performance in a multipath environment.

  As described above, according to the first embodiment, the data allocating unit 130 (302) distributes the known data (known symbol sequence) considering the delayed wave to the wireless communication device 100 (300) according to the pattern of the known data. A first threshold value detector 135 (311) for generating a first code determination threshold value from the known data having the first pattern, and a second value from the known data having the second pattern. Using a second threshold value detector 136 (312) for generating a code determination threshold value, and a threshold set including the first code determination threshold value and the second threshold value, reception is performed. A code determination unit 125 that performs code determination of the signal and outputs the code determination result as demodulated data.

  By doing so, a threshold set corresponding to intersymbol interference is generated using known data (known symbol sequence) in consideration of delayed waves, and an appropriate threshold is selected to perform code determination. Demodulation performance and communication quality in a path environment can be improved. In particular, demodulation performance caused by waveform distortion due to inter-symbol interference due to multipath in wireless transmission at a high data rate exceeding 1 Gsps, where inter-symbol interference occurs due to a delay difference of about 1 ns caused by a propagation distance difference of about 30 cm. Decrease can be prevented and communication quality is improved.

  Further, the wireless communication device 100 is provided with a threshold value switching unit 124 that selects a threshold value from a threshold set according to the code determination result performed immediately before by the code determination unit 125, and the code determination unit 125 The sign determination of the current symbol is performed using the selected threshold value.

(Embodiment 2)
The present embodiment is related to another configuration of the demodulation unit. As illustrated in FIG. 7, the demodulation unit 200 according to the present embodiment includes a first code determination unit 201, a second code determination unit 202, a threshold generation unit 123, and a sequence selection unit 205.

  The first code determination unit 201 selects a first threshold value from the threshold set generated by the threshold value generation unit 123, performs code determination, and outputs the first determination data.

  The second code determination unit 202 selects the second threshold value from the threshold set generated by the threshold value generation unit 123, performs code determination, and outputs the second determination data.

  If the immediately preceding demodulated data S117 is code “1”, sequence selection section 205 selects the first determination data that is the output of code determination section 201 and outputs it as demodulated data S117. Further, when the immediately preceding demodulated data S117 is a code “0”, the sequence selection unit 205 selects the second determination data that is the output of the code determination unit 202 and outputs it as demodulated data S117.

  FIG. 8 is a flowchart illustrating a processing procedure in the receiving unit including the demodulating unit 200. The movement by the components on the input side of the demodulator is the same as in FIG.

  In step 1001 to step 1003, a threshold set composed of first and second threshold values is generated based on sampling data of a symbol whose code is known within the preamble period.

  In step 2001, the code determination unit 201 performs code determination using the first threshold value, generates first determination data as a code determination result, and the code determination unit 202 sets the second threshold value. The used code determination is performed, and second determination data as a code determination result is generated.

  In step 2002, the sequence selection unit 205 determines whether the immediately preceding code is “1” or “0”.

  If it is determined in step 2002 that the immediately preceding code is “1”, first determination data is selected by the sequence selection unit 205 in step 2003 and output as demodulated data S117. If it is determined in step 2002 that the immediately preceding code is “0”, second determination data is selected by the sequence selection unit 205 in step 2004 and output as demodulated data S117.

  In the above description, the case where a threshold set composed of first and second threshold values corresponding to 1-bit intersymbol interference is generated has been described. Alternatively, a configuration may be adopted in which a threshold set corresponding to 2 bits or more is generated. In this case, the same number of code determination units as combinations that can be taken by the bits in the expected occurrence period of interference are prepared, and the sequence selection unit 205 generates interference corresponding to the latest code result from the determination data from each code determination unit. The determination data from the code determination unit for determining the code using the threshold value corresponding to the symbol pattern of the expected period is selected and output as demodulated data.

  As described above, according to the second embodiment, the demodulator 200 uses the first code determination threshold value to perform the first code determination unit 201 that performs code determination of the received signal, and performs the second code determination. Based on the code determination result of the code determination unit 201 and the code determination result of the code determination unit 202 based on the code determination result of the second code determination unit 202 that performs code determination of the received signal using the threshold And a sequence selection unit 205 that outputs the selected code determination result as demodulated data.

  By doing this, a decision data group is generated that is code-determined using each threshold value of the threshold set corresponding to inter-symbol interference due to multipath, and the decision data is selected according to the previous demodulated data as demodulated data. By outputting, it is possible to improve demodulation performance and communication quality in a multipath environment. Further, since it is not necessary to change the threshold value used in the code determination unit for each symbol in the data period of the communication frame, the power consumption in the demodulation unit can be reduced even when high-speed data transmission is supported. .

(Embodiment 3)
In the first and second embodiments, the description has been made on the assumption that the number of bits considering intersymbol interference is fixed. On the other hand, in the present embodiment, the multipath delay time, that is, the number of bits that should be considered for intersymbol interference is evaluated, and transmission / reception is performed using a known symbol sequence having a length corresponding to this evaluation.

  As shown in FIG. 9, radio communication apparatus 400 according to Embodiment 3 includes transmission / reception section 401 and control section 402. The transmission / reception unit 401 includes a reception unit 403 having a demodulation unit 404 and a multipath evaluation unit 405.

  The multipath evaluation unit 405 uses the multipath evaluation period in the received frame to evaluate the state of intersymbol interference due to the multipath environment. Note that in the multipath evaluation period in the frame, the control unit 402 of the wireless communication device 400 on the frame transmission side repeatedly transmits the PN4-stage M-sequence repetition data.

  Specifically, as shown in FIG. 10, the multipath evaluation unit 405 delays the sampling data S121 by a predetermined period by a delay unit 406 that delays by one symbol period and a positive / negative coefficient corresponding to the PN4 stage. An adder 407 for adding signals is formed.

  The multipath evaluation unit 405 having such a configuration takes a sliding correlation with the M sequence of the PN4 stage with respect to the sampling data S121 in the multipath evaluation period of the communication frame, thereby changing the correlation value S408 corresponding to the multipath. Is detected.

  The control unit 402 determines the occurrence state of intersymbol interference from a high correlation value generated at a position delayed with respect to the synchronization timing with the M sequence, and determines the number of bits to consider intersymbol interference due to multipath (this is , Corresponding to the length of the above-described known symbol string or the length of the expected interference occurrence period). Then, for example, the control unit 402 outputs the known symbol sequence length to the demodulation unit 404 and transmits it to the radio communication apparatus 400 on the frame transmission side via the transmission unit 114, the antenna duplexer 113, and the antenna 110. The frame in which the known symbol sequence corresponding to the known symbol sequence length is included in the preamble period is transmitted by radio communication apparatus 400 on the frame transmission side.

  Demodulation section 404 generates a threshold set in consideration of intersymbol interference corresponding to the known symbol string length from control section 402, similarly to demodulation sections 122 and 200 in the first and second embodiments. The code determination of the current symbol is performed using a threshold value obtained from the symbol pattern in the expected period of occurrence of interference having the same pattern as the symbol pattern that has already been subjected to code determination.

  In the above description, by using an M-sequence of PN4 stages, it becomes possible to cope with intersymbol interference due to a delayed wave having a propagation distance difference of about 4.5 m, and a radio communication system using a millimeter wave band. In this case, it is considered that sufficient performance can be obtained considering distance attenuation. However, a longer sequence or another pseudo-noise sequence having properties necessary for evaluating the correlation with the delayed wave may be used.

  As described above, the multipath evaluation unit 405 that evaluates the degree of intersymbol interference in the multipath evaluation period of the communication frame is provided, and the threshold is set using a known symbol sequence having a length corresponding to the evaluated degree of intersymbol interference. Since a value set can be generated, it can be applied to an arbitrary multipath environment, and demodulation performance can be improved.

  As described above, according to Embodiment 3, the code sequence (known symbol sequence) included in the threshold generation period of the communication frame is distributed to radio communication apparatus 400 according to the pattern, and the known data of each pattern is handled. A demodulator 404 that generates a threshold value, performs code determination of the received signal using the generated set of threshold values, and outputs the code determination result as demodulated data, and a multipath evaluation period of a communication frame A multipath evaluation unit 405 that evaluates propagation characteristics, a control unit 402 that generates and transmits information on the delay time of the multipath from the result of the evaluation, and changes the length of a code string distributed by the demodulation unit 404; Was established.

  The wireless communication device 400 on the transmission side of the communication frame has a multipath evaluation period for evaluating the propagation characteristics in wireless communication, and has a length corresponding to the multipath delay time fed back from the frame reception side. A radio frame having a threshold generation period including all combinations of the code strings is transmitted.

  In this way, a threshold set can be generated using a known symbol sequence having a length corresponding to the degree of intersymbol interference, so that it can be applied to any multipath environment, and can be used for demodulation performance and communication. Quality can be improved.

  INDUSTRIAL APPLICABILITY The radio communication apparatus and radio communication system according to the present invention can perform demodulation while suppressing a decrease in error rate and the like and can improve communication quality even when intersymbol interference due to multipath occurs. It is.

1 is a block diagram showing a configuration of a radio communication system and a radio communication apparatus according to Embodiment 1 of the present invention. The block diagram which shows the structure of the threshold value production | generation part of FIG. Diagram showing frame format The figure which shows the example of an analysis of the baseband signal which band-limited the detection signal of the radio | wireless communication apparatus of FIG. FIG. 1 is a flowchart for explaining the demodulation operation in the demodulator of FIG. The block diagram which shows the other structure of the demodulation part of FIG. FIG. 3 is a block diagram illustrating a configuration of a demodulation unit according to the second embodiment. FIG. 7 is a flowchart for explaining the demodulation operation in the demodulation unit of FIG. FIG. 3 is a block diagram illustrating a configuration of a wireless communication apparatus according to a third embodiment. The block diagram which shows the structure of the multipath evaluation part of FIG. Block diagram showing configuration of conventional demodulation means FIG. 11 is a diagram for explaining the ASK demodulation method in the received data specifying means of FIG.

Explanation of symbols

100, 400 Wireless communication device 110 Antenna 111, 401 Transmission / reception unit 112, 402 Control unit 113 Antenna duplexer 114 Transmission unit 115, 403 Reception unit 118 Detection unit 120 Sampling unit 122, 200, 300, 404 Demodulation unit 123, 301 Threshold Value generation unit 124, 319 Threshold switching unit 125 Code determination unit 130, 302 Data distribution unit 131, 133, 303, 305, 307, 309 Minimum value detection unit 132, 134, 304, 306, 308, 310 Maximum value Detection unit 135, 136, 311, 312, 313, 314 Threshold detection unit 201, 202 Code determination unit 205 Sequence selection unit 405 Multipath evaluation unit 406 Delay unit 407 Adder

Claims (14)

Data distribution means for distributing known data in consideration of delayed waves according to the pattern of the known data;
First threshold value generating means for generating a first code determination threshold value from the known data having a first pattern;
Second threshold value generating means for generating a second code determination threshold value from the known data having a second pattern;
Demodulating means for performing code determination of a received signal using a threshold set including the first code determination threshold and the second code determination threshold, and outputting a code determination result as demodulated data;
A wireless communication apparatus comprising: According to the code determination result performed immediately before by the demodulating means, comprising threshold selection means for selecting a threshold from the threshold set,
The radio communication apparatus according to claim 1, wherein the demodulation unit performs code determination of a current symbol using the selected threshold value. The known data includes code strings “11”, “10”, “01”, “00”,
The first threshold value generation means generates the first code determination threshold value from a code string of “11” and “10”,
The second threshold value generation means generates the second code determination threshold value from a code string of “01” and “00”,
The threshold selection means selects the first code determination threshold when the immediately preceding code determination result is “1”, and the second threshold when the immediately preceding code determination result is “0”. The wireless communication apparatus according to claim 2, wherein the code determination threshold value is selected. Third threshold value generating means for generating a third code determination threshold value from the known data having a third pattern;
Fourth threshold value generating means for generating a fourth code determination threshold value from the known data having a fourth pattern;
Comprising
The known data includes code strings “111”, “110”, “101”, “100”, “011”, “010”, “001”, “000”,
The first threshold value generating means generates the first code determination threshold value from a code string of “111” and “110”,
The second threshold value generation means generates the second code determination threshold value from a code string of “101” and “100”,
The third threshold value generation means generates the third code determination threshold value from a code string of “011” and “010”,
The fourth threshold value generation means generates the fourth code determination threshold value from a code string of “001” and “000”,
The threshold selection means selects the first code determination threshold when the immediately preceding code determination result is “11”, and the second threshold when the immediately preceding code determination result is “10”. The third code determination threshold is selected when the immediately preceding code determination result is “01”, and when the immediately preceding code determination result is “00”, the third code determination threshold is selected. The wireless communication apparatus according to claim 2, wherein a fourth code determination threshold is selected. The demodulating means includes
First code determination means for performing code determination of a received signal using the first code determination threshold;
Second code determination means for performing code determination of a received signal using the second code determination threshold;
Based on the code determination result performed immediately before, the code determination result of the first code determination unit and the code determination result of the second code determination unit are selected, and the selected code determination result is output as demodulated data. Sign determination selection means;
The wireless communication apparatus according to claim 1, further comprising: The known data includes code strings “11”, “10”, “01”, “00”,
The first threshold value generation means generates the first code determination threshold value from a code string of “11” and “10”,
The second threshold value generation means generates the second code determination threshold value from a code string of “01” and “00”,
The code determination selection unit selects the code determination result of the first code determination unit when the immediately preceding code determination result is “1”, and the first code determination selection unit selects the first code determination result when the immediately preceding code determination result is “0”. 6. The wireless communication apparatus according to claim 5, wherein the code determination result of the code determination means of 2 is selected. Third threshold value generating means for generating a third code determination threshold value from the known data having a third pattern;
Fourth threshold value generating means for generating a fourth code determination threshold value from the known data having a fourth pattern;
Third code determination means for performing code determination of a received signal using the third code determination threshold;
Fourth code determination means for performing code determination of a received signal using the fourth code determination threshold;
Comprising
The known data includes code strings “111”, “110”, “101”, “100”, “011”, “010”, “001”, “000”,
The first threshold value generating means generates the first code determination threshold value from a code string of “111” and “110”,
The second threshold value generation means generates the second code determination threshold value from a code string of “101” and “100”,
The third threshold value generation means generates the third code determination threshold value from a code string of “011” and “010”,
The fourth threshold value generation means generates the fourth code determination threshold value from a code string of “001” and “000”,
The code determination selection unit selects the code determination result of the first code determination unit when the immediately preceding code determination result is “11”, and the code determination selecting unit selects the first code determination result when the immediately preceding code determination result is “10”. 2 is selected, and when the immediately preceding code determination result is “01”, the code determination result of the third code determining unit is selected, and the immediately preceding code determination result is “00”. 6. The wireless communication apparatus according to claim 5, wherein the code determination result of the fourth code determination means is selected when   The wireless communication apparatus according to claim 1, wherein the data distribution unit distributes the known data included in a received frame according to a pattern of the known data. Receiving means for receiving a radio frame including all possible patterns of a symbol sequence consisting of a code determination target symbol and a symbol having a length expected to cause intersymbol interference with the code determination target symbol;
A distribution unit that distributes the symbol sequence according to a pattern of the symbol sequence;
Threshold value generating means for generating a code determination threshold value corresponding to each pattern of a symbol having a length expected to generate intersymbol interference based on a power value of the code determination target symbol;
Demodulating means for performing code determination of a received signal using a set of threshold values generated by the threshold value generating means, and outputting a code determination result as demodulated data;
A wireless communication apparatus comprising: A threshold value corresponding to a symbol having a length that is expected to cause the inter-symbol interference having the same pattern as the code determination result pattern performed immediately before by the demodulation means is selected from the threshold value set; A threshold selection means;
The radio communication apparatus according to claim 9, wherein the demodulation unit performs code determination of a current symbol using the selected threshold value. A radio transmission apparatus that transmits a radio frame having a threshold generation period including all combinations of code sequences having a length corresponding to a delay time due to multipath; and
Data distribution means for distributing a code string included in the threshold generation period according to a pattern, threshold generation means for generating a code determination threshold corresponding to known data of each pattern, and the threshold generation A radio reception apparatus comprising: demodulating means that performs code determination of a received signal using a set of code determination threshold values generated by the means and outputs a code determination result as demodulated data;
A wireless communication system comprising: The wireless transmission device transmits a wireless frame including a code string of “11”, “10”, “01”, “00” in the threshold generation period,
The threshold value generating means includes a first threshold value generating means for generating a first code determination threshold value from code strings “11” and “10”, and codes “01” and “00”. The wireless communication system according to claim 11, further comprising second threshold value generation means for generating a second code determination threshold value from the sequence. The wireless transmission device includes a multipath evaluation period for evaluating propagation characteristics in wireless communication, and includes all combinations of code sequences having a length corresponding to the delay time fed back from a frame reception side. Send a radio frame with a value generation period,
The wireless reception device evaluates propagation characteristics during the multipath evaluation period, and generates and transmits information on the delay time from the evaluation result, and the length of the code string distributed by the data distribution unit The wireless communication system according to claim 11, further comprising control means for changing The wireless transmission device includes an M-sequence data sequence in the multipath evaluation period,
The wireless communication system according to claim 13, wherein the evaluation unit evaluates propagation characteristics based on a sliding correlation between a received signal and the M sequence.

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