TW201703425A - Demodulation technique with power tracking - Google Patents

Abstract

A demodulation method includes the steps of: continuously tracking power of a target signal among signals received and correcting an estimated target-signal power value. The estimated power value is used as a reference during the demodulation process for determination of the target signal. The target signal could be accurately demodulated even when the power of the target signal is lower than that of an interference signal. The present invention also provides a signal power regulation method, performed in conjunction with the demodulation method, for continuously measuring the Signal-to-Interference and Noise Ratio (SINR), discovering in time an increase in a Bit Error Rate (BER), and notifying in advance the transmitting end to regulate transmission power. The methods prevent retransmission of data packets and excessive loss of energy at the transmitting end. Hence, the present invention is applicable to a body area network, which carries limited energy, for improvement of energy consumption by, for example, wearable or embedded sensors.

Description

Power tracking demodulation technology

The present invention relates to a demodulation method, in particular, by continuously tracking the power of a target signal analyzed in a received signal, and continuously correcting an estimated target signal power estimate, which is used as a demodulation. In the process of changing, the comparison determines which is the comparison reference of the target signal, and a demodulation method that can correctly demodulate the power of the target signal below the power of the interference signal .

In recent years, as the number of mobile devices continues to increase, mutual interference between different communication systems is becoming more and more common. However, the demodulation technology known to resist interference mostly improves the power of the transmitting end to transmit signals. Interfering with the power of the signal to ensure correct demodulation, but this solution will make the transmitter very power-hungry, especially in the case of co-channel interference, so for low-power communication systems, for example Medical human body area networks containing wearable or implantable electronic sensing devices will directly reduce the useful life of these electronic sensing devices using conventional demodulation techniques.

Therefore, in order to enable a target signal to be correctly demodulated when its power is lower than the power of an interference signal, the inventors have devoted themselves to research and propose the power tracking demodulation technology of the present invention. The power tracking demodulation technique includes a demodulation method and a power adjustment method coupled to the demodulation method.

The foregoing demodulation method includes: obtaining a target signal strength indicator (RSSI) by the average power of the RTS message in the RTS/CTS (Request To Send/Clear To Send) protocol, and defining the target signal power pre- Valuation.

According to the RTS/CTS (Request To Send/Clear To Send) protocol, a target signal strength indicator (RSSI) is obtained from the average power of the RTS message, thereby defining a target signal power estimate (X _RSSI ).

The received signal is split into a plurality of short signals according to the timing, each short signal has the same length of time, and each includes at least one component signal, and one of the component signals is the target signal.

For the short signal of the first time sequence, analyze the component signal of the first time and calculate the power value of each of the different component signals; and compare the power value to the target signal power estimate, and the closest to the power value. The component signal corresponding to the target signal power estimate is regarded as the target signal, and the rest is the at least one interference signal, and the target signal is demodulated.

For the short signal of the second timing, according to the power value corresponding to the target signal in the first timing, the target signal power estimated value in the first timing is corrected to obtain a target signal power estimation. The correction value is obtained by using the target signal power estimation correction value as a comparison reference, and finding the component signal whose power value is closest from the short signal of the second timing is regarded as the target signal, and the target signal is solved. Modulation.

For each short signal after the third timing, the target signal power prediction correction value in the previous timing is corrected according to the power value corresponding to the target signal in the previous timing, and the updated value is obtained. The target signal power estimation correction value is used as a comparison benchmark with the updated target signal power estimation correction value, and the component signal whose power value is closest is found from the current short signal signal, and is regarded as the target signal, and the target signal is regarded as the target signal. The target signal is demodulated.

The signal content of the target signal is obtained, and when the power of the target signal in the short signal is lower than the power of the interference signal, the frequency can still be correctly demodulated.

Further, the target signal and the interference signal are both frequency modulation signals and have respective code frequency. The received signal is subjected to short-time Fourier transform, and the received signal is split into the short signals according to timing. In each short signal, analyzing each symbol frequency and the corresponding power value thereof, and having the power value closest to the target signal power estimated value or the target signal power estimated correction value is regarded as the code frequency. The symbol frequency of the target signal is frequency-demodulated by the target signal according to the symbol frequency of the target signal.

Further, the length of the short signals is less than or equal to one-half of the length of the shortest code switching time in the interference signal, and the target signal is in each code, only corresponding to each symbol. A short signal or a plurality of short signals having a short signal with the largest difference in power values of the component signals, performing the foregoing power value comparison, and performing the foregoing target signal power estimation value or target signal power estimation correction value Correcting, by which the target signal is identified, and the updated target signal power prediction correction value is obtained, and the target signal is frequency-demodulated according to the symbol frequency of the target signal, and the updated target signal power is updated. The estimated correction value is used as the power value comparison for the target signal to be demodulated in the next symbol.

Further, the correction of the target signal power estimated value or the target signal power estimated correction value is performed by using a mixed average method, wherein the mathematical formula of the mixed average method is ,and Is a tracking correction method for continuous average method. Is a tracking correction method for direct feedback method. X _init indicates the target signal power estimated value defined by the average power of the RTS message, and X _tmp indicates the target signal power estimated value before the correction or the The target signal power prediction correction value, k represents the length of the historical data of the reference review, Δ represents a unitized weight value, and X _pass represents the power value of the target signal obtained by the analysis in the previous timing.

The foregoing power adjustment method includes:

Continuously recording the power value of the target signal obtained during the demodulation process, the power value of the interference signal, and the power value of a noise to obtain a signal interference noise ratio (Signal-to-Interference and Noise) Ratio, SINR); when the changed signal interference noise ratio is less than -22dB or greater than -12dB, a power adjustment is initiated, and the power adjustment includes:

A. a virtual first target signal power first adjustment value, according to the target signal power first adjustment value, the recorded power value of the interference signal and the power value of the noise, to obtain a virtual one signal interference noise The first adjustment value is greater than the first adjustment value, wherein the virtual signal interference noise is between -22 dB and -12 dB.

B. Obtain a virtual one-signal-to-noise ratio (SNR) according to the target signal power first adjustment value and the previously recorded power value of the noise.

C. If the virtual signal noise ratio is greater than or equal to 10 dB, the transmitting end adjusts the transmission power according to the first adjustment value of the target signal power; if the virtual signal noise ratio is less than 10 dB, step D is performed. .

D. a second adjustment value of the virtual target signal power, according to the second adjustment value of the target signal power, the recorded power value of the interference signal and the power value of the noise, to obtain a virtual one signal interference noise The second adjustment value is greater than 6 dB, and the transmitting end adjusts the transmission power according to the second adjustment value of the target signal power.

Further, the foregoing power adjustment method further includes a threat assessment to perform a period of evaluation before the signal interference noise ratio is less than -22 dB or greater than -12 dB, and then determine whether the foregoing power adjustment is needed. The assessment includes:

First, when the changed signal interference noise ratio is less than -22 dB or greater than -12 dB, the next N interference noise ratios of the signals are recorded, and the average of the interference noise ratios of the N signals is calculated. Where N is a random positive integer.

Then, if the average value of the N signal interference noise ratios is less than -22 dB or greater than -12 dB, the power adjustment is performed; if the average of the N signal interference noise ratios is between -22 dB and - This power adjustment is not required between 12dB.

The effect of the invention is:

1. continuously track and record the power value of the target signal to obtain the target signal power estimated value correction value, so as to compare the respective power values of the component signals during the demodulation change, thereby finding the target signal demodulation, borrowing Therefore, the target signal can be correctly demodulated when its power is lower than the power of the interference signal.

2. Demodulation using the demodulation method of the present invention, where the signal-to-interference and noise ratio (SINR) is between -20 dB and -15 dB (the power of the target signal is low at this time) When the power of the interference signal is), the bit error rate is less than 3%. Compared with the conventional demodulation method, the demodulation method of the present invention additionally develops a signal interference with a demodulation accuracy rate greater than 97%. Signal ratio (SINR) interval.

3. Using the demodulation method of the present invention, and in conjunction with the power adjustment method of the present invention, in the interference-to-interference noise ratio of the continuous tracking, it is possible to timely find that the bit error rate is likely to increase when an interference signal occurs. Therefore, the sender is notified to adjust the transmission power to cancel the risk of increasing the bit error rate. Therefore, the bit error rate is maintained below 10% during the entire demodulation process.

4. The present invention tracks the noise ratio by tracking its signal to ensure that the power adjustment is started at an appropriate timing, thereby avoiding the continuous operation of the power adjustment operation mechanism and increasing the energy loss.

5. The present invention actively tracks its signal interference noise ratio, so before the bit error rate is increased and the packet needs to be retransmitted, the power adjustment step is first started to reduce the bit error rate, and the packet retransmission is cancelled. Therefore, compared with the traditional demodulation method and the power adjustment mechanism of the collocation, the power adjustment mechanism is passively waited until the entire packet demodulation becomes wrong, and the power adjustment is started. The invention can eliminate the waste of energy for packet retransmission. It also reduces the energy waste caused by the demodulation error (that is, the bit demodulation becomes wrong), which effectively saves the energy of the transmitting end.

6. The invention has the effect of saving energy of the transmitting end, and can be applied to various small electronic devices, in particular, medical monitoring electronic sensors suitable for application on a human body area network system, such as wearable or implantable blood pressure. , heart rate sensor, etc., to make up for its small size, low energy, or the difficulty of removing the replacement of energy, and can effectively extend its service life.

In summary of the above technical features, the main effects of the power tracking demodulation technique of the present invention will be apparent from the following embodiments.

First, the embodiment includes a demodulation method and a power adjustment method in conjunction with the demodulation method.

Referring to the first figure and referring to the second figure, a process of demodulating a received signal (1) by using a demodulation method is described, so that an interference signal (11) exists in the When receiving the signal (1), it can still correctly demodulate from the receiving signal (1) a target signal (12) sent by a transmitting end (T).

Referring to the second figure, the demodulation method of the embodiment is used to demodulate one of the packets of the target signal. First, when a packet demodulation of the target signal starts, the RTS is first used by the RTS. The average power of the RTS message in the /CTS (Request To Send/Clear To Send) protocol obtains a Received Signal Strength Indication (RSI), thereby defining a target signal power estimate (X _RSSI ).

In this embodiment, the target signal and the interference signal are exemplified by a frequency modulation signal, and the target signal and the interference signal have respective code frequencies, and the short message is used when receiving the received signal. The Fourier transform technique divides the received signal into a plurality of short signals having the same length of time according to the timing, and analyzes the respective symbol frequencies included in the first short signal and the corresponding symbol frequencies. a power value that is compared to the aforementioned target signal power estimate (X _RSSI ), wherein the code frequency corresponding to the power value closest to the target signal power estimate (X _RSSI ) is regarded as The symbol frequency of the target signal, and the rest is the code frequency of the interference signal, and is found according to the code frequency corresponding to the power value closest to the target signal power estimate (X _RSSI ) After the target signal, the target signal is frequency-demodulated.

Then, for each short signal after the second timing, the target signal power estimate in the previous timing is based on the power value corresponding to the target signal in the previous timing (or already The corrected target signal power estimation correction value is corrected to obtain an updated target signal power estimation correction value (X' _RSSI ), and the target signal power estimation correction value (X' _RSSI ) is used as a ratio. For the reference, the nearest power value is found from the short signal of the current timing, and is regarded as the target signal, and the target signal is frequency-demodulated according to the symbol frequency corresponding to the target signal to obtain the content of the target signal. .

The foregoing steps are repeated until all the short signals in the foregoing packet are correctly demodulated, and then the demodulation of the next packet is entered.

When the foregoing demodulation method is used, since the power of the target signal in each short signal is continuously tracked, the power of the target signal in each short signal can be lower than the power of the interference signal. Correctly demodulate the target signal in each short signal.

Referring to the third figure, the short-time Fourier transform technique is used to split the received signal in a time domain into a plurality of short-time short signals according to the timing, and convert each short-term signal in the time domain into a frequency domain. After the spectrogram (a), each spectrogram (a) can be stacked into a set of 3D signal response graphs (A) with time and frequency according to time series, and the 3D signal response graph (A) Not only can you see the component signal in the received signal, but you can also see the change of the component signal over time. For example, you can see that the target signal (12) exists at the beginning, and the interference signal (11) is Appeared halfway.

Therefore, as long as the target signal power estimated value (X _RSSI ) is initially obtained and the received signal is split and analyzed using the short-time Fourier transform technique, the target signal power is obtained in the 3D signal response map. The evaluation (X _RSSI ) compares the power values of the component signals in the first timing to identify which is the target signal, and each short signal after the second timing, according to its previous timing The power value corresponding to the target signal identified in the target is corrected for the target signal power estimated value (or the corrected target signal power estimated correction value) in the previous sequence to obtain an update. after a correction target signal power estimated value (X _'RSSI), the target signal power to the updated estimate correction value (X' _RSSI) as compared to baseline, identify the power value from the current timing is the most number of SMS The proximity is regarded as the target signal, and the target signal is frequency-demodulated, and the above steps are repeated, and the target signal is continuously recognized and demodulated.

It should be noted that, in this embodiment, the target signal and the interference signal are, for example, frequency-modulated signals, but are not limited thereto, and the main focus is to split the received signals in time series. The instantaneous power is analyzed to facilitate the subsequent power value comparison. Therefore, if other types of modulation signals are used, the power value comparison is performed by splitting the signals according to the timing and analyzing the power, which is covered by the present invention. Within the scope.

Referring to the fourth A diagram, the fourth B diagram, and the fourth C diagram, an example is shown when an interference signal and a target signal are asynchronously switched with each other (as shown in FIG. 4A). In the short signals converted by the short-time Fourier transform technique, there will be some short signals, and there is an error between each code frequency and its corresponding power value, and the error degree and the short-time Fourier transform The sampling frequency is related to the length of time of each short signal mentioned above.

For example, in the fourth B diagram, when each time length captured by the short-time Fourier transform is one symbol time length of the target signal, the target signal is between the symbol time 0 and the symbol time 1. For low frequency and its power value is 1, the interference signal is high frequency and its power value is 4, however, after the short-time Fourier transform, in the spectrum diagram between the code time 0 and the code time 1 The lower frequency has a power value of 1, and the higher frequency has a power value of 2.5. Therefore, after the target signal power is estimated to be corrected (assuming an accurate estimate, it is 1), the The power value of the target signal is 1, and the power value of the interference signal is only 2.5, and the error value is 1.5. This is because the interference signal of the higher frequency does not exist at the beginning, and appears at the time of the symbol 0 to The symbol is after the time period 1, so after the short-time Fourier transform, the power of the higher frequency only shows the average power value of 2.5 in the symbol time 0 to the symbol time 1.

For example, in the fourth B picture, when between the symbol time 1 and the symbol time 2, the target signal is converted to a high frequency and its power value is 1 because of the code switching, and the interference signal is in the code. The time 1 to the code 2 of the previous time has not passed the code switching, so it is still high frequency and its power value is 4, and the interference signal has been in the large segment after the code time 1 to the code time 2 After the code switching, it is converted to low frequency and its power value is 4. However, after the short-time Fourier transform, the spectrum between the code time 1 and the code time 2 is lower, and the lower frequency is The power is 2.5, and the power of the higher frequency is 1.9. After the target signal power correction value (assumed to be an accurate estimate, it is 1), although the target signal is high frequency, However, the power value is 1.9, the error value is 0.9, and although the interference signal can be distinguished as a low frequency, the power value is 2.5 and the error value is 1.5, because the interference signal is based on the symbol time 1 to the code time. When it is between about 1.4, its frequency is the same as the high frequency of the target signal, and the code time is about 1.4 to between the code time 2, the interference signal is switched to a lower frequency, so after the short-time Fourier transform, the power value of the higher frequency includes the power of the target signal and the part of the interference signal. The power (i.e., the power value between the symbol time 1 and the symbol time is about 1.4), while the power value of the lower frequency only shows the average power in the symbol time 1 to the symbol time 2.

For another example, in the fourth C picture, when each time length captured by the short-time Fourier transform is changed to one-half of the length of the shortest code switching time in the interference signal, after the short-time Fourier transform, A total of two spectrograms are obtained between the symbol time 0 and the symbol time 1, that is, the code code time 0 to the symbol time 0.5 obtains the first picture, and the code time 0.5 to the code time 1 obtains the second picture, wherein The interference signal of the higher frequency appears midway between the symbol time 0 and the symbol time 0.5. Therefore, in the first spectrum diagram (a1), the power of the higher frequency is only shown in the The average power value 1 in the code time 0 to the symbol time 0.5 has an error, and between the symbol time 0.5 and the symbol time 1, since the higher frequency interference signal is not switched by the code, In the second spectrum diagram (a2), the lower frequency has a power value of 1, and the higher frequency has a power value of 4, which does reflect the target signal (12) and the interference signal (11). The power value of ).

For another example, in the fourth C picture, between the symbol time 1 and the symbol time 2, after the short-time Fourier transform, two spectrum images are obtained, that is, the symbol time 1 to the symbol time 1.5 is obtained, and the third picture is obtained. The fourth time is obtained from the code time 1.5 to the code time 2, wherein the target signal has been switched to a high frequency after the code switching, and the interference signal is only halfway between the code time 1 and the code time 1.5. Switching to a low frequency, therefore, in the third spectrum map (a3) after the short-time Fourier transform, the higher frequency has a power of about 3.1, and does not reliably reflect the power value of the target signal, and the The interference signal has been code-switched and remains at a low frequency between the code time 1.5 and the code time 2. Therefore, after the short-time Fourier transform, the fourth spectrum (a4) is compared. The high frequency has a power value of 1, and the lower power has a power value of 4, which does reflect the power value of the target signal (12) and the interference signal (11).

In summary, in the fourth C picture, when each time length captured by using the short-time Fourier transform is one-half of the length of the shortest code switching time in the interference signal, each of the target signals In the time length of the code switching, a spectrum map with the lowest error can be selected, which can truly reflect the true time of the target signal and the interference signal in the length of a code switching of the target signal. The power value, wherein the difference between the power value of the high frequency and the power value of the low frequency is selected as the spectrum with the lowest error, for example, the second spectrum from the left in the fourth C picture Figure (a2) and the fourth spectrum (a4).

In addition, it can also be known that when each time length captured by using the short-time Fourier transform is less than one-half of the length of the shortest code switching time in the interference signal, the same can be used in the target signal. In the length of a code switching time, the spectrum with the lowest error is selected. However, the shorter each time length captured by the short-time Fourier transform, the more spectrum patterns to be analyzed, and the receiving end. It will be possible that the speed of the analysis cannot keep up with the speed of signal reception due to too many spectrograms to be analyzed, so the length of each time captured by the short-time Fourier transform cannot be reduced indefinitely, which is also in line with Heisen. The description of the principle of the castle is not accurate.

Therefore, in the best case of the embodiment, the length of the short signals is one-half of the length of the shortest code switching time in the interference signal, so that each code of the target signal is ensured. In the length of time, at least one of the obtained spectrograms can completely reflect the respective power values of the target signal and the interference signal, that is, in the best case of the embodiment, the demodulation time is In the short signal corresponding to each code of the target signal, the power value comparison with the power value of each component signal is performed, and the foregoing power signal estimation value or target signal power estimation is performed. Correction of the correction value.

Therefore, when the flowchart shown in the second figure is used, the time length of each short signal in this embodiment is one-half of the shortest code switching length of the interference signal, and the received signal is to be demodulated. In order to obtain the content of the signal, the maximum value of the Fourier transform spectrum of the power value of the target signal and the power value of the interference signal is taken in the code length of each target signal, and the target signal and the interference signal are The discriminating method is a power spectrum value corresponding to each component signal of the component in which the power values are separated from each other, and the target signal power estimated value (X _RSSI ) or the target signal power estimated correction value (X′) _{The RSSI} is compared, wherein the target signal power estimated value or the target signal power estimated correction value is an estimate of the power of the target signal in the one of the short signals, that is, the target signal It is one of the component signals having the power value closest to the target signal power estimate (X _RSSI ) or the target signal power estimate correction value (X' _RSSI ).

In this embodiment, according to the power value corresponding to the target signal in the previous timing, when the target signal power estimated value or the target signal power estimated correction value in the short signal of the current timing is corrected, a mixed average method, and the mathematical formula of the mixed average method is ,among them Is a continuous correction method for tracking correction, and Is the tracking correction method of the direct feedback method, and X _init represents the target signal power estimation value defined by the average power of the RTS message, and X _tmp represents the target signal power prediction correction value before the correction, k Indicates the length of the historical data of the reference review, △ represents a unitized weight value, and X _pass represents the target signal power value obtained by the analysis in the previous timing.

Referring to Figures 5A and 5B, the computer simulation is used to simulate the hybrid signal averaging method to correct the target signal power estimate in the short signal. The actual power value comparison of the target signal shows that the mixed average method is used to track and estimate the value of the change (in this case, the power value of the target signal is affected by the variation of the communication channel). And continue to correct, the estimated value is very consistent with the actual value system. For example, in Figure 5A, when a target signal and an interference signal are used in the slow-change channel model in the communication channel theory, the mixed average is used. The method tracks and estimates the power of the target signal, and the predicted value is in good agreement with the actual value curve. As shown in the fifth B-picture, the target signal and an interference signal are in the communication channel theory. When the channel model is changed rapidly, the hybrid averaging method is used to track the power of the target signal and make an estimate. The predicted value and the actual value curve are also in good agreement.

Therefore, in combination with the above, it is also explained that in the embodiment, the target signal power estimation value or the target signal power estimation correction value as a comparison reference is corrected by using the hybrid averaging method. The power value of the target signal is correctly estimated even in the case of various variations of the communication channel, so the comparison result is highly accurate as the comparison reference. Therefore, when an interference signal appears and the power value of the interference signal is higher than the target signal during the process of receiving a received signal, the demodulation method of the embodiment can be used to correctly demodulate and change the signal. Target signal.

Next, the flow of use of the power adjustment method of the present embodiment will be described below, and the application of the aforementioned demodulation method will be described together with the application of the conventional demodulation method, and the respective demodulation becomes correct.

First, please refer to the sixth figure, which uses the program simulation operation to simulate with discrete events. Under the demodulation method of this embodiment, the demodulated signal interference noise ratio (Signal-to-Interference) is used. And Noise Ratio, SINR) plots the Bit Erro Rate (BER). Among them, it is defined as -22dB≦SINR≦-12dB interval and SINR≧6dB interval as safe zone (2), in -25dB≦SINR<-22dB interval, -12dB<SINR≦-9dB interval and 3dB≦SINR<6dB interval It is the warning zone (3), and the danger zone (4) is in the range of SINR<-25dB and -9dB<SINR<3dB, and the warning zone (3) and the danger zone (4) are defined as non-safe zones (also That is: SINR < -22 dB and -12 dB < SINR < 6 dB).

Referring to FIG. 7A, the main flow structure of the power adjustment method in this embodiment is: the SINR is continuously detected by the receiving end, and the transmitting end is detected by the detected SINR. It is found that the risk of receiving a signal error is about to increase (that is, the bit error rate is increased but it does not affect the need to retransmit the packet), but the packet retransmission is not required, and the sender is notified in time to adjust its transmission power. In order to release the risk of receiving a signal error, and the receiving end is also found by the new SINR that the risk of receiving errors has been reduced to an acceptable range (ie, the bit error rate has been reduced to an acceptable range), then the receiving end continues Detect SINR.

Referring to FIG. 7B and FIG. 7C together, the foregoing power adjustment method includes:

Continuously recording the power value of the target signal obtained during the demodulation process, the power value of the interference signal, and the power value of a noise to obtain a signal interference noise ratio (Signal-to-Interference and Noise) Ratio, SINR); when the changed signal interference noise ratio is less than -22dB or greater than -12dB, a power adjustment is initiated, and the power adjustment includes:

A. a virtual first target signal power first adjustment value, according to the target signal power first adjustment value, the recorded power value of the interference signal and the power value of the noise, to obtain a virtual one signal interference noise The first adjustment value is greater than the first adjustment value, wherein the virtual signal interference noise is between -22 dB and -12 dB.

B. Obtain a virtual one-signal-to-noise ratio (SNR) according to the target signal power first adjustment value and the previously recorded power value of the noise.

C. If the virtual signal noise ratio is greater than or equal to 10 dB, the transmitting end adjusts the transmission power according to the first adjustment value of the target signal power; if the virtual signal noise ratio is less than 10 dB, step D is performed. .

D. a second adjustment value of the virtual target signal power, according to the second adjustment value of the target signal power, the recorded power value of the interference signal and the power value of the noise, to obtain a virtual one signal interference noise The second adjustment value is greater than 6 dB, and the transmitting end adjusts the transmission power according to the second adjustment value of the target signal power.

Referring to FIG. 7D, the foregoing power adjustment method further includes a threat assessment, where the signal interference noise ratio is less than -22 dB or greater than -12 dB, and then a short period of time is evaluated before deciding. Whether the aforementioned power adjustment is required, wherein the threat assessment includes:

First, when the changed signal interference noise ratio is less than -22 dB or greater than -12 dB, the next N interference noise ratios of the signals are recorded, and the average of the interference noise ratios of the N signals is calculated. Where N is a random positive integer.

Then, if the average value of the N signal interference noise ratios is less than -22 dB or greater than -12 dB, the power adjustment is performed; if the average of the N signal interference noise ratios is between -22 dB and - This power adjustment is not required between 12dB.

Referring to FIG. 7E, the actual operation process of the threat assessment method is described in detail by using a flowchart. First, when the changed signal interference noise ratio is less than -22 dB or greater than -12 dB, then the At the beginning of the threat assessment, a positive integer N is randomly generated, then the SINR of the currently demodulated symbol is recorded, and after the SINR of the currently demodulated symbol is recorded, N is decremented by 1 and then demodulated. Changing the next N-1 symbols and continuously decreasing the positive integer N until the positive integer N is decremented to 0, calculating the average value of the SINR recorded during the period in which the positive integer N is decremented to 0, and Comparing the foregoing figure in the sixth figure, that is, the SINR corresponding to the BER, when the average value of the recorded SINR is between -22 dB and -12 dB, it is expressed as a short SINR, for example, an environment. There is a sudden occurrence of high-frequency pulse noise, or the receiving end receiving the received signal has a very short reception abnormality, and the abnormality lasts only one or two symbols, and then immediately returns to normal, therefore, In this case, it is not necessary to start the power adjustment, change The signal interference noise ratio (SINR) has gradually returned to the original safety zone -22dB ≦ SINR ≦ -12dB; conversely, when the average value of the recorded SINR continues to be less than -22dB or greater than -12dB, It means that there is indeed a high-powered interference source and continuously generates an interference signal, so the power adjustment needs to be started immediately to maintain the correctness of the demodulation.

In summary, according to the threat assessment method, the power adjustment can be avoided only because of a very short reception abnormality, and after a very short period of abnormal reception, an additional power adjustment is required, which is redundant.

The power tracking demodulation technology and the conventional operation of the present embodiment will be described below by using a simulation program to simulate a static situation (moving rate 0 km/Hr.) and a running movement state (28.8 km/Hr.). In the demodulation technology, the power tracking demodulation technology of this embodiment is different from the traditional demodulation technology, and the parameters of the simulation program and the simulation scenario are illustrated in Table 1 below. Table I

Referring to FIG. 8A, FIG. 8B, FIG. 9A and FIG. 9B, the demodulation method in the power tracking type demodulation technique of the present embodiment is used, respectively, and the conventional demodulation method is used. In the static situation and the running situation, the difference between the bit error rate, the packet loss situation and the total transmission power loss of transmitting the packet.

First, in the eighth A picture and the ninth A picture, the traditional demodulation method is based on selecting a higher energy symbol on the spectrogram during decision making, so when the signal interference ratio is lower than 0 dB (ie, the interference signal is smaller than the target signal) Strong), the demodulation result is due to the strong interference signal, leading to the bit error rate rising to around 50%, no higher reason is because the code only has 0 and 1 when the message content When it is a random data sequence, it can be known from the central limit theorem that half of the probability that the interference message is the same as the target message will occur. Therefore, no bit error will occur regardless of whether the demodulation result follows the interference signal or the target signal. When the demodulation method of the embodiment is used, even if the interference signal strength is higher than the target signal, the signal interference ratio is in the range of -24dB to -10dB, and the ratio of the bit error can be effectively reduced to less than 10%, but It is noted that the demodulation method of the embodiment relies on the accuracy of the signal power tracking. Therefore, when the signal interference ratio is close to zero, the bit error rate is higher because the power of the target signal is tracked. And when used to correct the target signal power prediction correction value, the algorithm used (in this embodiment, the hybrid averaging method) is easy to have an error when the interference signal is close to the target signal, or to track the power of the interference signal. The value (the highest bit error rate of computer simulation results is nearly 30%), therefore, if you want to reduce the bit error rate of this interval (that is, when the signal interference ratio is close to 0), you need to be able to judge more accurately. What is the target signal in the received signal, so only a more powerful and accurate target signal power prediction value tracking correction calculation method can be achieved, and in this embodiment, the mixed average method is used for explanation. And there is a certain degree of accuracy. However, the algorithm for tracking correction of the target signal power prediction correction value is not limited to the hybrid averaging method, and can be accurately predicted by known numerical data and its changing trend. The tracking correction calculation method for estimating the next numerical data can be used for the present invention. In addition, when the demodulation method of the embodiment is used, when the signal interference ratio is lower than -25 dB, the reason why the bit error rate is increased is because the white noise and the entrained white noise are excessive when the interference intensity is too high. The sideband signal energy of the dispersion phenomenon has approached or even exceeded the intensity of the target signal, and masked all the signal characteristics of the target signal, so that the target signal could not be demodulated smoothly, so if the demodulation is successful, the target signal must be improved. Power, or design and control of the Spectrum Mask of the RF signal. As described in the present paragraph, in the demodulation method of the present embodiment, when there is an interference signal, the bit error rate after demodulation is different than that by using the conventional demodulation method under different signal interference ratios. When the modulation is low, and the interval is increased (that is, the signal interference noise ratio is -22dB to -12dB, the interference signal power is stronger than the target signal power in this interval), which can effectively reduce the bit error rate to Below 10%, it greatly improves the correct rate of demodulation.

Furthermore, in the eighth B and ninth B diagrams, in the conventional demodulation method, as long as the interference signal strength is greater than the target signal strength, the packet loss rate is 100%, which means that regardless of the transmitted power setting. Why, as long as a packet encounters interference from other high-power signals during transmission, the energy consumed to transmit the packet is wasted. However, if the demodulation method of the present embodiment is used, since there is still a very low bit error rate in the interval where the signal interference noise ratio is -22 dB to -12 dB, the probability of success in transmitting the packet for the first time is successful. Very high, and the packet loss rate is extremely low.

Referring to FIG. 10A, FIG. 10B, FIG. 11A and FIG. 11B, the demodulation method using the demodulation method of the embodiment is used for demodulation, but respectively When the power adjustment method proposed in this embodiment is used, the difference between the bit error rate, the packet loss situation, and the total transmission power loss of transmitting the packet in the static scenario and the running scenario, respectively. In FIG. 10A and FIG. 11A, it can be seen that when the power adjustment method proposed in this embodiment is adopted, the signal interference noise ratio is below a different value, and the corresponding bit error rate is There is a significant improvement, and the bit error rate is maintained below 10%, which means that after using the power adjustment method of the embodiment, the bit error of 10% or less can be maintained regardless of the power of the interfering signal. Rate, while avoiding the waste of packet retransmission. In addition, in the tenth B and eleventh B, when the power adjustment method proposed in this embodiment is used, in the case of different signal interference noise ratios, when the power adjustment method is not used, The loss rate of the packet has a reduced efficiency. The total power loss of a single packet transmission is slightly higher than that of a single packet without using the power adjustment method only in the vicinity of 0 dB and -25 dB. This is due to the start of the power adjustment. The power required is slightly increased. However, as a whole, the power adjustment method proposed in this embodiment is used, and the power adjustment method is not used, and the total transmission power loss of a single packet is significantly reduced.

In view of the foregoing description of the embodiments, the operation and the use of the present invention and the effects of the present invention are fully understood, but the above described embodiments are merely preferred embodiments of the present invention, and the invention may not be limited thereto. Included within the scope of the present invention are the scope of the present invention.

(1)‧‧‧ receiving signals
(11)‧‧‧Interference signals
(12) ‧ ‧ target signal
(2) ‧ ‧ safe area
(3) ‧‧‧Warning Area
(4) ‧‧‧Danger zone
(R) ‧ ‧ receiving end
(T)‧‧‧Send
(a) ‧ ‧ spectrum map
(A) ‧‧3D signal response diagram
(a1) ‧‧‧first spectrogram
(a2) ‧‧‧Second spectrogram
(a3) ‧ ‧ third spectrum map
(a4) ‧ ‧ fourth spectrogram

[Front diagram] is used to cooperate with the second figure to jointly illustrate a receiving end using the demodulation method of this embodiment to demodulate a received signal containing one of the target signals.

[Second Picture] is a flowchart for correct demodulation of a target signal of a packet from a received signal using the demodulation method of the present embodiment.

[Third image] is a 3D signal response diagram with two variables of time and frequency converted by using the short-time Fourier transform technique.

[Fourth A picture] is a signal diagram of a time domain when a received signal has an interference signal and a target signal which are mutually asynchronous switching codes.

[Fourth B] shows that the signal map of the time domain in the fourth A picture is converted by the short-time Fourier transform technique, and obtains a plurality of frequency-domain spectrum patterns arranged in time series, wherein the short-time Fourier transform is captured. Each time length is a symbol length of the target signal.

[Fourth C picture] shows that the signal map of the time domain in the fourth A picture is converted by the short-time Fourier transform technique, and obtains a plurality of frequency-domain spectrum patterns arranged in time series, wherein the short-time Fourier transform is captured. Each time length is one-half of the length of the shortest code switching time in the interference signal.

[Fifth A] is a graph illustrating the correction of the target signal power value by the hybrid averaging method under the slow change communication channel, and the corrected result is in good agreement with the actual power value of the target signal. .

[Fifth B] is a graph illustrating the correction of the target signal power value by the hybrid averaging method under the fast change communication channel, and the corrected result is in good agreement with the actual power value of the target signal.

[Sixth Diagram] is a graph showing the relationship between the obtained signal interference noise and the bit error rate by the discrete event simulation in the demodulation method of the present embodiment.

[Seventh A] The main structure of the power adjustment method of the present embodiment will be described by a flowchart.

[Seventh B] The timing of the power adjustment step in the power adjustment method of the present embodiment will be described by a flowchart.

[Seventh C] is a flowchart of the power adjustment step in the power adjustment method of the embodiment.

[Seventh D] is a flow chart illustrating the present embodiment. A threat evaluation step is included in the power adjustment method.

[Seventh E] is a flowchart of the threat evaluation step in the power adjustment method of the embodiment.

[Embodiment 8] is a graph showing the relationship between the respective signal interference noise ratio and the bit error rate in the static scenario using the demodulation method of the present embodiment and using the conventional demodulation method.

[Embodiment B] is a program simulation in a static scenario, using the demodulation method of the present embodiment and using a conventional demodulation method, respectively, in both the packet loss rate and the total transmission power loss of transmitting the packet, Their respective strips and graphs.

[Ninth AA] is a graph showing the relationship between the respective signal interference noise ratio and the bit error rate in the running mobile scenario using the demodulation method of the present embodiment and using the conventional demodulation method.

[Fig. 9B] is a program simulation in the running mobile scenario, using the demodulation method of the present embodiment and using the conventional demodulation method, respectively, in the packet loss rate and the total transmission power loss of transmitting the packet. , their respective strips and graphs.

[Tenth AA] is a program simulation in the static situation, using the demodulation method of the embodiment, and with or without the power adjustment method of the embodiment, the respective signal interference noise ratio and bit Meta error rate relationship graph.

[Tenth Bth diagram] is a program simulation in the static scenario, using the demodulation method of the embodiment, and when matching or not matching the power adjustment method of the embodiment, respectively, the packet loss rate and the transmission of the packet Of the total transmission power loss, their respective strips and graphs.

[11th A] is a program simulation in the running mobile scenario, using the demodulation method of the embodiment, and with or without the power adjustment method of the embodiment, the respective signal interference noise ratio A graph of the relationship with the bit error rate.

[Fig. 11B] is a program simulation in the running mobile scenario, using the demodulation method of the embodiment, and when matching or not matching the power adjustment method of the embodiment, respectively, in the packet loss rate and transmitting the Of the total transmission power loss of the packet, their respective strips and graphs.

Claims (6)

A demodulation method for demodulating a receiving end to include a receiving signal of a target signal to obtain a signal content of the target signal, wherein the receiving signal selectively includes at least one interference signal, The demodulation method includes: obtaining a target signal strength indicator (RSSI) by the average power of the RTS message in the RTS/CTS (Request To Send/Clear To Send) protocol, and defining the target signal power estimation value; The received signal is split into a plurality of short signals according to the timing, each short signal has the same length of time, and each includes at least one component signal, and one of the component signals is the target signal; for the first timing a short signal, analyzing a component signal thereof, and calculating a power value of each of the different component signals; comparing the power value to the target signal power estimated value, and estimating the power value closest to the target signal power The component signal corresponding to the value is regarded as the target signal, and the rest is the at least one interference signal, and the target signal is demodulated; for the second timing The short signal is corrected according to the power value corresponding to the target signal in the first sequence, and the target signal power estimated value in the first sequence is corrected to obtain a target signal power prediction correction value, The target signal power prediction correction value is used as a comparison reference, and the component signal whose power value is closest is found from the short signal of the second timing, and is regarded as the target signal, and the target signal is demodulated; Each short signal after three timings is corrected according to the power value corresponding to the target signal in the previous timing, and the target signal power estimation correction value in the previous timing is corrected, and the updated target is obtained. The signal power estimation correction value is used as a comparison reference with the updated target signal power estimation correction value, and the component signal whose power value is closest is found from the current short signal signal, and is regarded as the target signal, and the target signal is Demodulation is performed; by which, the signal content of the target signal is obtained. The demodulation method of claim 1, wherein the target signal and the interference signal are frequency modulation signals and have respective code frequencies, and the received signals are subjected to short-time Fourier transform. Splitting the received signal into the short signals according to the timing, and analyzing each symbol frequency and the corresponding power value in each short signal, the power value being closest to the target signal power estimated value or the target The symbol frequency of the signal power estimation correction value is regarded as the symbol frequency of the target signal, and the target signal is frequency-demodulated according to the symbol frequency of the target signal. The demodulation method of claim 2, wherein the short signals are less than or equal to one-half of the length of the shortest code switching time of the interference signal, and the target signal is In a code, only one short signal or a plurality of short signals corresponding to each code has a short signal having the largest difference in power values of the component signals, and the power value comparison and the foregoing are performed. Correcting the target signal power estimated value or the target signal power estimated correction value, thereby identifying the target signal, and obtaining the updated target signal power prediction correction value, according to the symbol frequency of the target signal The signal is frequency demodulated, and the updated target signal power prediction correction value is used for comparing the target signal to the next symbol for power value comparison. The method for demodulating a variable according to claim 1, wherein the target signal power estimated value or the target signal power estimated correction value in the short signal is corrected by a hybrid averaging method to obtain a new one. The target signal power prediction correction value, the mathematical formula of the hybrid average method is ,among them Is a continuous correction method for tracking correction, and Is the tracking correction method of the direct feedback method, and X _init represents the target signal power estimation value defined by the average power of the RTS message, and X _tmp represents the target signal power prediction correction value before the correction, k Indicates the length of the historical data of the reference review, △ represents a unitized weight value, and X _pass represents the target signal power value obtained by the analysis in the previous timing. The demodulation method of claim 1, further comprising a power adjustment method for adjusting a transmission power of the transmitting end transmitting the target signal, including: obtaining the continuous recording and demodulating process The power value of the target signal, the power value of the interference signal, and the power value of a noise to obtain a signal-to-interference and noise ratio (SINR); When the interference noise ratio is less than -22dB or greater than -12dB, a power adjustment is initiated, and the power adjustment includes: A. a first adjustment value of the virtual target signal power, and the first adjustment value according to the target signal power Obtaining a virtual one signal interference noise ratio first adjustment value, wherein the virtual signal interference noise ratio is between -22dB and -12dB; B. according to the target signal power first adjustment value Obtaining a virtual signal-to-noise ratio (SNR); C. if the virtual signal-to-noise ratio is greater than or equal to 10 dB, the transmit power of the transmitting end is first according to the target signal power The adjustment value is adjusted; if the virtual signal noise ratio is less than 10 dB, step D is performed; D. virtual second target signal power second adjustment value, and virtual one signal interference is obtained according to the second adjustment value of the target signal power And comparing the second adjustment value, wherein the virtual signal interference noise is greater than 6 dB than the second adjustment value, and the transmission power of the transmission end is adjusted according to the second adjustment value of the target signal power. The demodulation method described in claim 5 of the patent application further includes a threat assessment to perform a period of evaluation before the signal interference noise ratio is less than -22 dB or greater than -12 dB, and then determine Whether the power adjustment needs to be performed, the threat assessment includes: when the changed signal interference noise ratio is less than -22 dB or greater than -12 dB, recording the next N interference noise ratios of the signal, and calculating the The average of the N signal interference noise ratios, where N is a random positive integer; if the average of the N signal interference noise ratios is less than -22 dB or greater than -12 dB, then the Power adjustment; if the average of the N signal interference noise ratios is between -22dB and -12dB, the power adjustment is not required.