JP2006157216A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver capable of optimally setting a threshold value of a comparator even when an interference wave by another user exists in a reception band and decreasing a bit error rate. <P>SOLUTION: The receiver includes a band pass filter 17, a detector 18, an integrater 19, and an A/D converter 20 as a reception system for detecting a noise level in addition to a reception system for demodulating wireless transmission data, can select noise and an interference wave even when the interference wave of the other user exists in the wireless transmission data reception band, detects an accurate S/N and sets the threshold value of the comparator for discriminating the code in an optimal state so as to thereby reduce the bit error rate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a receiving apparatus that receives a signal modulated by a modulation method such as Amplitude Shift Keying (hereinafter ASK), ON-OFF Keying (hereinafter OOK), Pulse Position Modulation (hereinafter PPM).

  Conventionally, in the ASK receiver, the threshold value of the comparator with the best bit error rate varies depending on the signal-to-noise power ratio (hereinafter referred to as SN ratio), and when the SN ratio is poor (when small), the SN ratio is good. It is known that the bit error rate can be improved by increasing the threshold value of the comparator (when it is large) (see Non-Patent Document 1, for example).

Further, in the detection circuit used in the ASK receiver, the sign is determined by averaging with an ASK reception signal integrator and comparing the divided voltage with the output of the detector as a threshold value. The composition is known. According to this configuration example, the threshold value of the comparator can be changed according to the received power (see, for example, Patent Document 1).
Kiyoki / Seki Kiyozo, “Basics of Digital Modulation and Demodulation”, Ohmsha, published August 10, 1984, pp. 30-35 JP 2004-80112 A (page 7, FIG. 3)

  However, the threshold value varying means of the comparator described in Patent Document 1 varies according to the received power of the received signal, and is optimal when there is an interference wave of other communications in the received band. The value cannot be set. For example, according to Non-Patent Document 1, it is necessary to make the threshold value larger when the SN ratio is worse (smaller) than when the SN ratio is good (large).

  However, when an interference wave of another user exists in the reception band, the threshold value variable means of the comparator described in Patent Document 1 sets the threshold value on the assumption that the SN ratio is better as the integrator output voltage is larger. When the interference wave exists, the threshold is set by the total power of the received power of the desired signal and the power of the interference wave, so that the SN ratio is good even though the SN ratio is deteriorated by the interference wave. The threshold value is set to deteriorate the bit error rate.

  The present invention has been made in view of the above-described conventional circumstances, and even when there is an interference wave by another user in the reception band, the threshold value of the comparator can be optimally set, and a bit error An object of the present invention is to provide a receiving apparatus capable of reducing the rate.

  A receiving apparatus of the present invention includes a first receiving system that receives a modulated data, having a comparator that compares a received signal with a threshold value, a bandpass filter that detects noise power other than the modulated data receiving band, and a detection A comparison circuit provided in the first reception system in accordance with a ratio of a reception power of the modulated data and a detected out-of-band noise power, a second reception system having an integrator, an integrator, and an AD converter; Receiving signal processing means for controlling the threshold value of the detector.

  With this configuration, the threshold value of the comparator can be changed according to the reception signal-to-noise ratio.

  In the receiving apparatus of the present invention, the received signal processing means compares the received signal power and the noise power to calculate a signal-to-noise power ratio, and the result and the bit error rate are within a preset range. If there is no interference wave, set the threshold according to the threshold table of the optimized comparator, and if the bit error rate is worse than the preset range, optimize with the interference wave The threshold value is set according to the offset addition to the threshold value table or the reference threshold value table of the comparator.

  With this configuration, the threshold value of the comparator can be set to the best state even when the S / N ratio is deteriorated by the interference wave within the reception band.

  In the receiving apparatus of the present invention, the frequency band assigned to the radio astronomy that is not used for other communications is used as the receiving band of the second receiving system.

  With this configuration, accurate noise power can be detected.

  According to the present invention, it is possible to provide a receiving apparatus capable of optimally setting a threshold value of a comparator and reducing a bit error rate even when an interference wave from another user is present in a reception band. Can do.

  FIG. 1 is a block diagram showing a schematic configuration of a receiving apparatus according to an embodiment of the present invention. The receiving apparatus of the present invention receives a signal modulated by a modulation method such as Amplitude Shift Keying (hereinafter referred to as ASK), ON-OFF Keying (hereinafter referred to as OOK), Pulse Position Modulation (hereinafter referred to as PPM).

  As shown in FIG. 1, the receiving apparatus of this embodiment includes an antenna 1, a bandpass filter 2 that limits a reception band, an LNA 3 that amplifies a high-frequency signal, a mixer 4 that converts a frequency, and a local oscillator 5 And a variable gain amplifier 6 used for automatic gain control (AGC).

  In addition, as a reception system for receiving the modulation data, a bandpass filter 7 that passes the frequency-converted modulation signal, a detector 8 that detects the modulation signal, an integrator 9 that smoothes the detected signal, and a reception An AGC control circuit 10 that optimally controls the level, a comparator 12 that compares the detected signal with a comparison voltage serving as a threshold and determines the sign, and a latch circuit 13 that latches the output of the comparator 12; And a DA converter 15 for generating a comparison voltage of the comparator.

  Further, as a receiving system for detecting noise power, a band-pass filter 17 that passes the noise detection band, a detector 18 that detects noise, an integrator 19 that rectifies the detected noise, and a noise level are sampled. And an AD converter 20 for converting into digital data.

  A reception signal processing unit 22 is provided for controlling the reception signal processing and the threshold value output to the comparator 12.

  Next, a configuration example of the receiving apparatus will be described with reference to FIG. 1 and FIG.

  FIG. 2A shows an example of a frequency band received by the receiving apparatus of the present invention. The data communication band uses a band of 24.0 to 29.0 GHz, and the noise detection uses a band of 23.6 to 24.0 GHz allocated to radio astronomy.

In FIG. 1, the antenna 1, the bandpass filter 2 a, and the LNA 3 have an operation band of 23.6 to 29.0 GHz that is a data communication band and a noise detection band, and are frequency-converted by the mixer 4. When the oscillation frequency of the local oscillator 5 connected to the mixer 4 is 23.0 GHz, the output of the mixer 4 is
fRF ± fLo
However, since the purpose of the frequency conversion here is to reduce the frequency to a frequency that can be easily processed, the frequency of fRF-fLo is used.

  In this case, the output frequency of the mixer 4 is converted to a noise detection band (radio wave astronomy band) of 0.6 to 1.0 GHz and a data communication band of 1.0 to 6.0 GHz as shown in FIG. .

  In FIG. 1, a band pass filter 6 selects a data communication band, and a 1.0 to 6.0 GHz band is used as a pass band as shown in FIG. In FIG. 1, the bandpass filter 17 selects a noise band, and has a pass band of 0.6 to 1.0 GHz as shown in FIG.

  Next, the operation of the OOK receiving apparatus will be described with reference to FIGS.

  3A shows a transmission clock, FIG. 3B shows transmission data, and FIG. 3C shows an example of an OOK modulated wave. FIG. 3D shows an example of an input waveform of the detector 8 shown in FIG. 1 when it is affected by the interference of other users via the spatial transmission path. FIG. 3E shows the output of the detector 8 shown in FIG.

  FIG. 3F shows the input of the comparator 12 shown in FIG. An interference signal of another user is also input to the comparator 12. At this time, by appropriately changing the comparison voltage 16 shown in FIG. 1 according to the level of the interference wave, the communication quality of the interference wave is improved. Degradation can be minimized.

  FIG. 3G shows the output of the comparator 12 shown in FIG. In FIG. 1, the output of the comparator 12 is latched by the latch circuit 13 with the reception clock 24 to decode the data. FIG. 3H shows the reception clock, and FIG. 3I shows the latch circuit output.

  On the other hand, FIG. 3 (J) shows the input of the detector 18 shown in FIG. 1, and (K) shows the output of the detector 18. Compared with the input of the detector 8, interference from other users is removed by the band-pass filter 17, so that only the thermal noise is input to the detector 18. By integrating the output of the detector 18 with the integrator 19 and sampling it with the AD converter 20, the noise level in the band of the bandpass filter 17 in this receiving apparatus can be measured. FIG. 3 (L) shows the output of the integrator 20. Here, the SN ratio can be measured by comparing the measured noise level with the reception level report signal 23 from the AGC control circuit.

  The bandwidth of the band-pass filter 17 is within the radio astronomy band shown in FIG. 2C and may be known in advance. If the band ratio conversion with the band-pass filter 7 for selecting the data communication band in FIG. The SN ratio can be calculated.

  Next, setting of a threshold value that minimizes the SN ratio and the bit error rate will be described with reference to FIGS. FIG. 4 shows the calculation of the relationship between the SN ratio, threshold value, and bit error rate in ASK according to Non-Patent Document 1 described above. In the bit error rate of FIG. 4, E and the subsequent numbers indicate powers of 10 numbers.

The bit error rate Pe when the threshold value is ρ0 and the SN ratio is R is expressed by Equation 1.

  Here, Pe, M → S indicates the probability of mistaken M → S, and is expressed by the following equation (2).

  However, Φ (y) represents an error function and is expressed by the following equation (3).

  FIG. 5 shows a threshold value at which the bit error rate is minimized according to the result of FIG. The threshold values shown here are normalized by a maximum of 1.

  Next, the setting of the threshold when affected by the interference of other users will be described with reference to FIG. FIG. 6 is a conceptual diagram showing the relationship between the SN ratio, the reference value of the bit error rate, and the reception state.

  In the case of the point 31 where the relationship between the SN ratio measured in accordance with the above in FIG. 6 and the bit error rate is on the reference value, it is determined that there is no interference power of other users, and according to the threshold table without interference wave in FIG. The comparison voltage 16 of the comparator 12 is set. As an example of the table used here, the characteristics shown in FIG. 5 can be used.

  On the other hand, in the case of the point 32 in FIG. 6 where the relationship between the measured SN ratio and the bit error rate deviates from the reference value, it is assumed that it is affected by interference from other users, and the bit error rate reference value and the SN ratio are The difference 33 is calculated. The threshold value can be optimized by using a threshold value table shifted by the calculated SN ratio difference 33 or by adding an offset of the SN ratio difference 33 to the reference threshold value table. it can.

  FIG. 7 shows an outline of the flow of the above processing. The reception signal processing unit 22 shown in FIG. 1 has the reception data decoding function and the function of FIG. 7 including bit error rate measurement.

  The reception signal processing unit 22 detects the AGC control voltage based on the reception signal level report signal 23 from the AGC control circuit 10 (step S701). Further, the noise level is detected from the noise level report signal 21 output from the AD converter 20 (step S702). Based on the detected AGC control voltage and noise level, the S / N ratio of the received signal is calculated (step S703). Further, the bit error rate is detected from the result of processing the received signal (step S704).

  The received signal processing unit 22 compares the SN ratio calculated in step S703 with the bit error rate detected in step S704, and determines whether the relationship is appropriate (step S705). For this determination, as shown in FIG. 6, a bit error rate reference value is used.

  If the relationship between the SN ratio and the bit error rate is appropriate, a threshold is set as no interference wave (step S706). On the other hand, if the relationship between the S / N ratio and the bit error rate is not appropriate, the difference from the reference value of the S / N ratio is calculated (step S707), and a threshold value is set as an interference wave (step S708).

  According to the receiving apparatus of the embodiment of the present invention, the threshold value of the comparator can be optimally set even when there is an interference wave by another user within the reception band, and the bit error rate is reduced. Can be made.

  The receiving apparatus of the present invention has the effect that the threshold value of the comparator can be optimally set even when there is an interference wave by another user within the reception band, and the bit error rate can be reduced, This is useful for a receiving apparatus using the ASK method, a UWB receiving apparatus using the OOK or PPM method, and the like.

The block diagram of the receiver in embodiment of this invention The figure explaining the receiving frequency and the band of a band pass filter in embodiment of this invention Conceptual diagram of demodulation operation in an embodiment of the present invention The figure which shows the relationship of the SN ratio of ASK, the threshold value of a comparator, and the bit error rate in the embodiment of the present invention The figure which shows the relationship of the threshold value of the comparator with the best bit error rate and the signal to noise ratio of ASK in the embodiment of the present invention. The conceptual diagram which shows the relationship between the reference value of SN ratio, the bit error rate, and a receiving state in embodiment of this invention The figure explaining the operation | movement of the comparator threshold value setting in embodiment of this invention

Explanation of symbols

1 Antenna 2 Bandpass filter 3 LNA
4 Mixer 5 Local Oscillator 6 Variable Gain Amplifier 7 Band Pass Filter 8 Detector 9 Integrator 10 AGC Control Circuit 11 AGC Control Voltage 12 Comparator 13 Latch Circuit 14 Comparison Voltage Control Data 15 DA Converter 16 Comparison Voltage 17 Band Pass Filter 18 Detection Unit 19 Integrator

Claims (3)

A first receiving system for receiving modulated data, having a comparator for comparing the received signal with a threshold;
A second reception system having a bandpass filter, a detector, an integrator, and an AD converter for detecting noise power other than the modulation data reception band; and the reception power of the modulation data;
Received signal processing means for controlling a threshold value of the comparator provided in the first receiving system in accordance with a ratio with detected noise power outside the band;
A receiving device. The receiving device according to claim 1,
The received signal processing means calculates the signal-to-noise power ratio by comparing the received signal power and the noise power. If the result and the bit error rate are within a preset range, the received signal processing means is optimal with no interference wave. The threshold value table of the comparator is optimized in the presence of an interference wave when the threshold value is set according to the threshold value table of the optimized comparator and the bit error rate is worse than a preset range Or the receiving apparatus which sets the said threshold value according to the offset addition with respect to a reference | standard threshold value table. The receiving device according to claim 1,
The receiving apparatus of the second receiving system uses a frequency band assigned to a radio astronomy that is not used for other communications.

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