WO2022052056A1 - Procédé et appareil de détection de symbole, et système - Google Patents

Procédé et appareil de détection de symbole, et système Download PDF

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Publication number
WO2022052056A1
WO2022052056A1 PCT/CN2020/114855 CN2020114855W WO2022052056A1 WO 2022052056 A1 WO2022052056 A1 WO 2022052056A1 CN 2020114855 W CN2020114855 W CN 2020114855W WO 2022052056 A1 WO2022052056 A1 WO 2022052056A1
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Prior art keywords
symbol
value
received signal
energy
energy difference
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PCT/CN2020/114855
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English (en)
Chinese (zh)
Inventor
邵帅
张治�
钟财军
饶磊
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Oppo广东移动通信有限公司
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Priority to CN202080100080.1A priority Critical patent/CN115428365B/zh
Priority to PCT/CN2020/114855 priority patent/WO2022052056A1/fr
Publication of WO2022052056A1 publication Critical patent/WO2022052056A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received

Definitions

  • the present application relates to the field of wireless communication, and in particular, to a method, device and system for symbol detection.
  • the environmental backscattering system is a system that uses the radio frequency signals widely existing in the surrounding environment to realize the information transmission between the electronic tag and the reader, thereby greatly reducing the energy consumption.
  • the reader needs to detect the symbol sent by the electronic tag.
  • the reader is configured with a centralized antenna, and the multiple centralized antennas use the received signal vector to construct a decision threshold. During detection, the reader compares the matrix operation value of the received signal with the decision threshold, and derives the symbol sent by the electronic tag.
  • Embodiments of the present application provide a method, device and system for symbol detection. By configuring a plurality of distributed antennas in a reader, a better diversity gain can be obtained, which is helpful for symbol detection and improves the accuracy of symbol detection.
  • the technical solution is as follows.
  • a method for detecting symbols which is applied in a reader equipped with a plurality of distributed antennas, and the method includes:
  • the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol;
  • the original symbol corresponding to the first received signal is determined.
  • a method for detecting symbols is provided, which is applied in an environmental backscatter system, the environmental backscatter system includes: an electronic tag and a reader, the reader is equipped with a plurality of distributed antennas , the method includes:
  • the electronic tag backscatters the first radio frequency signal according to the original symbol
  • the reader determines a first antenna of the plurality of distributed antennas
  • the reader receives a first received signal through the first antenna, and the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol;
  • the reader determines the original symbol corresponding to the first received signal.
  • a symbol detection device which is applied in a reader, the reader is equipped with a plurality of distributed antennas, and the device includes: a determining module and a receiving module;
  • the determining module configured to determine the first antenna in the plurality of distributed antennas
  • the receiving module is configured to receive a first received signal through the first antenna, where the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol;
  • the determining module is configured to determine the original symbol corresponding to the first received signal.
  • a reader includes a programmable logic circuit and/or program instructions for implementing the symbol detection method described in the above aspect when the reader is running.
  • an environmental backscatter system includes: an electronic tag and a reader, the reader is equipped with a plurality of distributed antennas;
  • the electronic tag is used for backscattering the first radio frequency signal according to the original symbol
  • the reader for determining a first antenna in the plurality of distributed antennas
  • the reader is configured to receive a first received signal through the first antenna, where the first received signal includes a second received signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol. radio frequency signal;
  • the reader is configured to determine the original symbol corresponding to the first received signal.
  • a computer-readable storage medium having executable instructions stored in the readable storage medium, the executable instructions being loaded and executed by a processor to implement the symbols described in the above aspects Detection method.
  • a computer program product comprising computer instructions stored in a computer-readable storage medium, from which a processor of a computer device reads the computer instruction, the processor executes the computer instruction, so that the computer device executes the symbol detection method described in the above aspects.
  • the large-scale fading experienced by the received signals of each antenna is different, and a better diversity gain can be obtained, which is helpful for It is used to detect symbols and improve the accuracy of symbol detection.
  • FIG. 1 is a schematic diagram of mark inversion coding provided by an exemplary embodiment of the present application
  • FIG. 2 is a schematic diagram of a distributed environment backscattering system provided by an exemplary embodiment of the present application
  • FIG. 3 is a schematic diagram of an energy comparison detection method provided by an exemplary embodiment of the present application.
  • FIG. 4 is a flowchart of a method for symbol detection provided by an exemplary embodiment of the present application.
  • FIG. 5 is a flowchart of a method for symbol detection provided by an exemplary embodiment of the present application.
  • FIG. 6 is a schematic diagram of mark inversion coding provided by an exemplary embodiment of the present application.
  • FIG. 7 is a schematic diagram of bit error rate comparison provided by an exemplary embodiment of the present application.
  • FIG. 8 is a schematic diagram of a comparison of training symbol lengths provided by an exemplary embodiment of the present application.
  • FIG. 9 is a structural block diagram of a symbol detection apparatus provided by an exemplary embodiment of the present application.
  • CMI Coded Mark Inversion
  • the mark inversion code encodes the original symbol "0" as a zero for half a bit time, followed by a one for half a bit time, corresponding to "01"; and encodes the original symbol "1" as a constant level for a full bit time.
  • the 1-bit level alternates every time a "1” is encoded, corresponding to "00" or "11".
  • the original symbol is: 100110; the encoded symbol is: 110101001101.
  • Rayleigh Fading In a wireless communication channel, due to the multipath propagation of the signal to reach the receiving point, the field strength comes from different propagation paths, the delay time of each path is different, and the superposition of component waves in each direction , resulting in a standing wave field strength, resulting in rapid signal fading called Rayleigh fading.
  • the reader is configured with multiple antennas, and the positions of the multiple antennas are distributed and scattered around the reader. Compared with the centralized antenna, the distance between the antennas of the distributed antenna is larger.
  • FIG. 2 shows a schematic diagram of a distributed environmental backscattering system provided by an exemplary embodiment of the present application.
  • the distributed environmental backscattering system includes: an environmental radio frequency signal source 210, an electronic tag 220 with a single antenna, and a reader 230 configured with multiple distributed antennas.
  • the working process of the distributed environmental backscatter system is as follows: the environmental radio frequency signal source 210 sends a radio frequency signal to activate the electronic tag 220, the electronic tag 220 uses the backscatter communication technology to modulate its own information on the radio frequency signal, and the reader 230 receives electronic The reflected signal of the tag 220 is demodulated, so as to realize the information transmission between the reader 230 and the electronic tag 220 .
  • the ambient radio frequency signal source 210 is a radio frequency signal source in the environment around the electronic tag, and the ambient radio frequency signal source 210 includes, but is not limited to, TV, cellular or Wi-Fi signals.
  • the environmental device signal source 210 is used as the excitation source of the distributed environmental backscattering system to activate the electronic tag.
  • the ambient radio frequency signal source 210 can be divided into two categories, one is that in a complex communication environment, the ambient radio frequency signal 210 is modeled as a zero-mean complex Gaussian random variable; the other is that the radio frequency signal in the environment has a specific modulation method , such as Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Quadrature Amplitude Modulation (QAM), etc., which are considered to be unknown in this system. deterministic signal.
  • FSK Frequency Shift Keying
  • PSK Phase Shift Keying
  • QAM Quadrature Amplitude Modulation
  • the electronic tag 220 is an information sending node that reflects the radio frequency signal incident from the ambient radio frequency signal source 210 to different degrees.
  • the information on the electronic tag end is sent through the reflection modulation signal.
  • the electronic tag 220 performs mark inversion encoding on the original symbol, and decides to reflect (bit "1") or not reflect (bit "0") radio frequency according to the mark inversion code Signal.
  • the reader 230 is an information receiving node that demodulates the information by detecting the reflected signal from the electronic tag 220 .
  • the reader 230 can detect the original symbol transmitted by the electronic tag through an energy comparison detection method.
  • the reader 230 is configured with multiple distributed antennas, that is, the number of distributed antennas is not less than two.
  • the distributed antennas can be connected to the reader 230 through physical lines (low-loss cables), and the distributed antennas are scattered around the reader 230 .
  • the distributed antenna may include: antenna A 1 , antenna A i and antenna AL and so on.
  • h st , h tri and h sri respectively represent the ambient radio frequency signal source 210 to the electronic tag 220 , the electronic tag 220 to the i-th antenna A i of the reader 230 and the ambient radio frequency signal source 210 to the reading
  • the channel parameters between the i-th antenna A i of the controller 230 are assumed, and the channel in FIG. 2 is assumed to be a Rayleigh channel that remains unchanged within the coherence time of the same symbol and changes independently within the coherence time of different symbols.
  • FIG. 3 shows a schematic diagram of an energy comparison detection method provided by an exemplary embodiment of the present application.
  • the electronic tag performs sign inversion coding on N 2 original symbols, and encodes N 2 consecutive original symbols "0" into N 2 consecutive "01" for transmission, where N 2 is an integer greater than 0.
  • the reader receives the second received signal through the plurality of distributed antennas.
  • the reader calculates the first average energy A i and the second average energy B i of the second received signal received by the ith distributed antenna.
  • the first average energy A i is the energy average value of the second received signal in the first half of the N 2 symbol periods, corresponding to "0" in the sign inversion code
  • the second average energy B i is the average value of the energy of the second received signal in the second half of the N 2 symbol periods, corresponding to "1" in the mark inversion code.
  • the reader performs selective combining of signals received by multiple distributed antennas, selects the branch with the largest difference between A i and B i , and discards other branches.
  • the branch is selected as the first antenna, and the first average energy and the second average energy of the first antenna are denoted as A t and B t .
  • the first average energy A t is the average energy value of the signal received by the first antenna
  • the second average energy B t is the energy average value of the signal received by the first antenna.
  • the electronic label performs mark-reversal encoding on the N 1 original symbols.
  • the reader receives the first received signal through the first antenna.
  • the reader calculates the energy of the front and back parts of the first received signal in each symbol period, which are respectively recorded as and where k represents the kth original symbol in the kth symbol period. Then there are the following detection methods:
  • the calculation of the first average energy A i and the second average energy B i received by the i-th distributed antenna can use the following formulas:
  • N 2 is the number of symbol periods corresponding to the second received signal (that is, the number of original symbols)
  • N is the number of sampling points of symbols in each mark inversion code
  • j is the energy in the j-part time of the mark-reversal code of the k-th original symbol received by the i-th distributed antenna, where j ⁇ a,b ⁇ .
  • the first average energy and the second average energy corresponding to the first antenna selected in the collection stage are denoted as A t and B t , then the determination threshold Th in the detection method can be obtained by using the following formula:
  • Th M ⁇
  • FIG. 4 shows a flowchart of a symbol detection method provided by an exemplary embodiment of the present application.
  • the method can be applied to the distributed environmental backscattering system as shown in FIG. 2 .
  • the environmental backscattering system includes: an environmental radio frequency signal source, an electronic tag and a reader, and the reader is equipped with a plurality of distributed antennas.
  • the method may include the following steps:
  • Step 410 the ambient radio frequency signal source sends a first radio frequency signal.
  • the ambient RF signal source is the RF signal source in the environment around the electronic tag.
  • the environmental radio frequency signal source supports sending the first radio frequency signal for activating the electronic tag.
  • Exemplary ambient RF signal sources include, but are not limited to, television, cellular or Wi-Fi signals.
  • Step 420 the electronic tag backscatters the first radio frequency signal according to the original symbol.
  • the original symbol is a symbol generated at the electronic tag, and the electronic tag backscatters the first radio frequency signal sent by the ambient radio frequency signal source according to the original symbol.
  • the electronic tag is backscattered directly from the original symbol at itself. For example, when the original symbol is "0", the electronic tag does not reflect the first radio frequency signal; when the original symbol is "1", the electronic tag reflects the first radio frequency signal.
  • the electronic tag after encoding the original symbol, performs backscattering according to the encoded original symbol.
  • This embodiment of the present application does not limit the coding mode used. For example: when the symbol after encoding and converting the original symbol is "0", the electronic tag does not reflect the first radio frequency signal; when the symbol after encoding and converting the original symbol is "1", the electronic tag reflects the first radio frequency signal .
  • Step 430 the reader determines the first antenna among the plurality of distributed antennas.
  • the reader is configured with multiple distributed antennas.
  • Distributed antenna means that the positions of multiple antennas of the reader are distributed and scattered around the reader. Compared with the centralized antenna, the distance between the antennas of the distributed antenna is larger.
  • the positions of the reader's antenna A 1 , antenna A i and antenna AL are not close together. Since the reader is configured with distributed antennas, the large-scale fading experienced by the received signals of each antenna is different, and better diversity gain can be obtained.
  • the first antenna is an antenna branch finally used by the reader when performing symbol detection.
  • the first antenna is the antenna with the closest distance to the electronic tag among the multiple distributed antennas. This embodiment of the present application does not limit the manner in which the reader determines the first antenna among the multiple distributed antennas.
  • Step 440 the reader receives the first received signal through the first antenna.
  • the reader After determining the first antenna among the multiple distributed antennas, the reader discards other distributed antennas and uses the first antenna to receive the first received signal.
  • the first received signal is the signal received by the reader during the detection phase.
  • the detection stage is a time period during which the environmental backscattering system performs information exchange and information exchange in order to realize information transmission.
  • the reader needs to detect the original symbol corresponding to the first received signal.
  • the original symbol corresponding to the first received signal is unknown to the reader, and the reader needs to perform detection through a certain detection method to determine the original symbol.
  • the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol.
  • the second radio frequency signal may be a signal after the electronic tag reflects the first radio frequency signal, or may be an empty signal (that is, the electronic tag does not reflect the first radio frequency signal).
  • the first received signal may further include at least one of the following: a first radio frequency signal corresponding to the ambient radio frequency signal source, and a noise signal.
  • the reader when the electronic tag reflects the first radio frequency signal according to the symbol information, the reader will receive the first radio frequency signal, the reflected first radio frequency signal and the noise signal; when the electronic tag does not reflect the first radio frequency according to the symbol information signal, the reader will receive: the first radio frequency signal and the noise signal.
  • Step 450 the reader determines the original symbol corresponding to the first received signal.
  • the reader After receiving the first received signal, the reader detects the first received signal through a symbol detection method, and determines the original symbol corresponding to the first received signal.
  • the embodiment of the present application does not limit the symbol detection method specifically adopted by the reader.
  • the method provided in this embodiment by configuring a plurality of distributed antennas for the reader, compared with the method of configuring the centralized antenna for the reader in the related art, the large-scale fading experienced by the received signal of each antenna exists. If the difference is different, a better diversity gain can be obtained, which is helpful for symbol detection and improves the accuracy of symbol detection.
  • the electronic tag performs mark-reversal coding on the original symbol.
  • the mark inversion code is a non-return-to-zero line code.
  • the two-digit mark-reversal code corresponding to the original symbol d k is When the "0" code is input, the encoding output "01", and when the "1" code is input, the encoding output is "00" and "11" alternately.
  • the input is: 100110; the encoded output is: 110101001101.
  • the reader can use the determination threshold to perform symbol detection through energy comparison detection.
  • energy comparison detection refer to the following examples for details.
  • FIG. 5 shows a flowchart of a method for symbol detection provided by an exemplary embodiment of the present application, and the method can be applied to the distributed environment backscattering system shown in FIG. 2 .
  • step 420 can be alternatively implemented as: step 421 and step 422 ;
  • step 430 can be alternatively implemented as: steps 431 to 433 ;
  • step 450 can be alternatively implemented as: step 451 .
  • the method includes:
  • Step 410 the ambient radio frequency signal source sends a first radio frequency signal.
  • the ambient RF signal source is the RF signal source in the environment around the electronic tag.
  • the environmental equipment signal source is used as the excitation source of the distributed environmental backscattering system, and the environmental radio frequency signal source sends a first radio frequency signal for activating the electronic tag.
  • the first radio frequency signal sent by the ambient radio frequency signal source is denoted as s[n].
  • Step 421 the electronic tag performs sign inversion coding on the original symbol.
  • Step 422 the electronic tag backscatters the first radio frequency signal according to the original symbol encoded by the sign inversion code.
  • the electronic label performs sign inversion encoding on the original symbol, and obtains the original symbol encoded by the sign inversion code, and performs backscattering according to the original symbol encoded by the sign inversion code.
  • the electronic tag backscatters the first radio frequency signal according to the original symbol encoded by the sign inversion code
  • the obtained second radio frequency signal s b [n] is expressed as:
  • ⁇ is the reflection coefficient of the electronic tag
  • h st is the ambient RF signal source to the electronic tag. between the channel parameters, is the encoded symbol.
  • Step 431 the reader receives the second received signal through the multiple distributed antennas respectively.
  • the second received signal is the signal received by the reader during the estimation phase.
  • the estimation stage is the time period during which the environmental backscattering system performs information exchange in order to determine the decision threshold required for detection.
  • the original symbols corresponding to the second received signal in the estimation stage are known to the reader, for example, the original symbols are all 0, and the original symbols encoded by the sign inversion code are all 01.
  • the i-th distributed antenna of the reader simultaneously receives the first radio frequency signal, the second radio frequency signal and the noise signal, i is a positive integer not greater than N 2 , so the second reception of the i-th distributed antenna
  • the signal y i [n] has:
  • each channel parameter obeys Rayleigh fading whose variance is related to distance:
  • step 432 the reader determines the average energy difference.
  • the second received signal corresponds to N 2 symbol periods.
  • the average energy difference is the absolute value of the difference between the first average energy and the second average energy
  • the first average energy is the average energy of the second received signal in the first half of the N 2 symbol periods
  • the second average energy is the average value of the energy of the second received signal in the second half of the N2 symbol periods.
  • the first average energy is the average energy corresponding to 0 in the sign inversion code
  • the second The average energy is the average of the energy corresponding to 1 in the mark inversion code.
  • the original symbol is "00000”, and the original symbol encoded by the mark inversion code is "0101010101".
  • the first average energy is the average energy value of the second received signal received by any one of the distributed antennas during the first half symbol periods of symbol period 1, symbol period 2, symbol period 3, symbol period 4, and symbol period 5,
  • the second average energy is the average energy value of the second received signal received by any one of the distributed antennas during the second half of the symbol period of symbol period 1, symbol period 2, symbol period 3, symbol period 4 and symbol period 5 .
  • the electronic tag encodes N 2 consecutive original symbols "0" into N 2 consecutive "01"s for transmission, that is, the number of symbol periods corresponding to the second received signal is N 2 , and the reader calculates the i-th root distribution.
  • the first average energy A i and the second average energy B i of the signal received by the antenna are calculated as:
  • N 2 is the number of symbol periods corresponding to the second received signal (that is, the number of original symbols)
  • N is the number of sampling points of symbols in each mark inversion code
  • j is the energy in the j-part time of the mark-reversal code of the k-th original symbol received by the i-th distributed antenna, where j ⁇ a,b ⁇ .
  • the reader determines the average energy difference to be
  • Step 433 the reader determines the distributed antenna corresponding to the largest average energy difference as the first antenna.
  • the largest average energy difference is the i-th average energy difference
  • the first antenna is the i-th distributed antenna.
  • the reader records
  • the reader determines the product between the maximum average amount difference and the coefficient as the determination threshold.
  • the decision threshold Th M ⁇
  • M is a coefficient
  • the coefficient is a value greater than 0 and less than 1.
  • Step 440 the reader receives the first received signal through the first antenna.
  • the first received signal corresponds to N 1 symbol periods.
  • Step 451 for the ith symbol period in the N 1 symbol periods, the reader determines that the first received signal corresponds to the ith symbol period according to the relationship between the energy difference in the ith symbol period and the judgment threshold. original symbol.
  • the energy difference value is the energy difference value between the signal energy value of the first received signal in the second half symbol period and the signal energy value in the first half symbol period.
  • the signal energy of the first received signal in the second half symbol period is The signal energy value of the first received signal in the first half symbol period is Then the energy difference is It can be understood that the energy difference can be positive, 0, or negative.
  • step 451 includes: when the absolute value of the energy difference is greater than the determination threshold, the reader determines that the original symbol corresponding to the i-th symbol period of the first received signal is 0; When the value is less than the determination threshold, the reader determines that the original symbol corresponding to the i-th symbol period of the first received signal is 1.
  • the absolute value of the energy difference is greater than the judgment threshold, it means that the signal energy values in the first and last half symbol periods within the ith symbol period are quite different, so the ith symbol period may be for "01", that is, the original symbol is 0. Since the absolute value of the energy difference is less than the decision threshold, it means that the signal energy values in the first and last half symbol periods within the i-th symbol period have a small difference, so the i-th symbol period may be for "00" or "11", That is, the original symbol is 1.
  • the signal energy value corresponding to symbol 0 in the mark inversion code is smaller than the signal energy value corresponding to symbol 1, that is, A t ⁇ B t .
  • the energy difference is a positive value and the energy difference is greater than the determination threshold, it is determined that the original symbol corresponding to the i-th symbol period of the first received signal is 0; when the energy difference is negative, and the energy difference is When the absolute value of is greater than the judgment threshold, it is determined that the detection has an error.
  • the energy difference is a positive value, and when the energy difference is greater than the judgment threshold, it corresponds to "01" in the sign inversion code, indicating that the original symbol is 0; the energy difference is a negative value, and When the absolute value of the energy difference is greater than the judgment threshold, it corresponds to the "10" that does not exist in the mark inversion code, indicating that the detection is wrong.
  • the signal energy value corresponding to symbol 0 in the mark inversion code is greater than the signal energy value corresponding to symbol 1, that is, A t >B t .
  • the energy difference is a negative value, and the absolute value of the energy difference is greater than the judgment threshold, which corresponds to "01" in the sign inversion code, indicating that the original symbol is 0; the energy difference is a positive value , and when the energy difference is greater than the judgment threshold, it corresponds to the "10" that does not exist in the mark inversion code, indicating that an error occurs in the detection.
  • the above steps 410 to 451 show an energy comparison detection method for symbol detection.
  • an exemplary maximum a posteriori criterion (Maximum A Posteriori, MAP) detection method is introduced below.
  • the electronic tag performs sign inversion encoding on the original symbol, and the reader compares the energy difference (ie, the energy difference) between the front and rear half of each sign inversion with the judgment threshold. , so as to decode the original symbols.
  • This method only involves energy comparison and does not require complex matrix operations, so it is easier to implement.
  • the method provided by the embodiment of the present application uses distributed antennas and performs selective combination, and can select the antenna closest to the electronic tag as the first antenna through the average energy difference value, and maximize the average energy difference value, so that the subsequent When the symbol detection is performed according to the average energy difference, the obtained symbol detection result is more reliable.
  • ambient radio frequency signal sources can be divided into two categories, the following analyzes the performance of the energy comparison detection method proposed in the embodiments of the present application under two different ambient radio frequency signals (zero mean complex Gaussian ambient radio frequency signal and determined unknown ambient radio frequency signal). performance.
  • bit error rate (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 + (0.05 * (1 +
  • the total bit error rate is:
  • the total bit error rate is:
  • M is the coefficient in the decision threshold
  • N is the number of sampling points of the symbols in each mark inversion code.
  • M is the coefficient in the decision threshold
  • N is the number of sampling points of the symbols in each mark inversion code.
  • FIG. 7 a schematic diagram of bit error rate comparison provided by an exemplary embodiment of the present application is shown.
  • the energy comparison detection method provided in the embodiment of the present application is superior to the energy detection method provided in the related art.
  • the energy detection method means that the energy detector constructs the test statistic—the decision threshold by averaging the received signal energy of all symbols transmitted in the coherence time. After the signal is received, its energy is converted into a decision variable and compared with the decision threshold, so as to decode the signal of the electronic tag.
  • the energy detection method relies on all the symbols transmitted within the coherence time to estimate the decision threshold, which introduces a certain communication delay, and is only suitable for the situation where two binary symbols are sent with equal probability, and the actual operability is not strong.
  • the energy comparison detection method proposed in the embodiment of the present application performs better than the energy detection method when the signal-to-noise ratio is higher than 4 dB. Both methods have a BER floor, but the energy comparison detection method has a lower BER floor. At the same time, when the number of sampling points is increased, the accuracy of calculating the energy of the first level and the energy of the second level can be improved, and the performance of the bit error rate corresponding to the energy comparison detection method will be close to the optimal value in Figure 7, which can be further improved. performance.
  • FIG. 8 a schematic diagram of length comparison of training symbols provided by an exemplary embodiment of the present application is shown. Wherein, the energy comparison detection method provided in the embodiment of the present application is superior to the energy detection method provided in the related art.
  • the h tri from the electronic tag to each distributed antenna obeys a complex Gaussian distribution with a mean variance of 20, and the number of distributed antennas is 5.
  • the antennas of the energy detection method are concentrated in the same position, and the channel coefficient from the electronic tag to the centralized antenna obeys the complex Gaussian distribution with the same variance (mean value is 20).
  • mean value is 20.
  • set the probability of the transmitted symbol "0" as 0.1 it can be seen that the bit error rate of the energy detection method is higher than that of the energy comparison detection method proposed in the embodiment of the present application.
  • Increasing the length of the training symbol string is conducive to improving the accuracy of parameter estimation.
  • the energy comparison detection method proposed in the embodiment of the present application requires a shorter length, which can effectively reduce the communication delay.
  • the steps performed by the reader can be independently implemented as a symbol detection method on the reader side
  • the steps performed by the electronic tag can be implemented independently as a symbol detection method on the electronic tag side.
  • FIG. 9 shows a structural block diagram of a symbol detection device provided by an exemplary embodiment of the present application.
  • the device can be implemented as a reader, or be implemented as a part of a reader.
  • the reader is equipped with multiple distributed antennas.
  • the apparatus includes: a determining module 901 and a receiving module 902;
  • a determining module 901 configured to determine a first antenna among the multiple distributed antennas
  • a receiving module 902 configured to receive a first received signal through a first antenna, where the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol;
  • the determining module 901 is configured to determine the original symbol corresponding to the first received signal.
  • the electronic tag adopts sign inversion coding for the original symbol, and the first received signal corresponds to N1 symbol periods;
  • Determining module 901 is used to determine that the first received signal is within the i-th symbol period according to the relationship between the energy difference in the i-th symbol period and the decision threshold for the i-th symbol period in the N 1 symbol periods the corresponding primitive symbol;
  • the energy difference value is the energy difference value between the signal energy value of the first received signal in the second half symbol period and the signal energy value in the first half symbol period.
  • the determining module 901 is configured to determine that the original symbol corresponding to the i-th symbol period of the first received signal is 0 when the absolute value of the energy difference is greater than the determination threshold; the determining module 901 , for determining that the original symbol corresponding to the ith symbol period of the first received signal is 1 when the absolute value of the energy difference is smaller than the determination threshold.
  • the signal energy value corresponding to the symbol 0 in the sign inversion code is smaller than the signal energy value corresponding to the symbol 1;
  • the determining module 901 is configured to be a positive value when the energy difference value is positive and the energy difference value In the case of being greater than the determination threshold, determine that the original symbol corresponding to the first received signal in the i-th symbol period is 0; the determination module 901 is used for the negative value of the energy difference, and the absolute value of the energy difference is greater than the determination threshold In the case of , determine that there is an error in the detection.
  • the signal energy value corresponding to the symbol 0 in the sign inversion code is greater than the signal energy value corresponding to the symbol 1; the determining module 901 is configured to be a negative value when the energy difference value is negative and the energy difference value In the case where the absolute value of , is greater than the determination threshold, determine that the original symbol corresponding to the first received signal in the i-th symbol period is 0; the determination module 901 is used to determine if the energy difference is a positive value, and the energy difference is greater than the determination threshold. In the case of , determine that there is an error in the detection.
  • the receiving module 902 is configured to respectively receive the second received signal through multiple distributed antennas, and the second received signal corresponds to N 2 symbol periods; the determining module 901 is configured to determine the average energy difference value, the average energy difference is the absolute value of the difference between the first average energy and the second average energy, and the first average energy is the energy average of the second received signal in the first half of the N 2 symbol periods. value, the second average energy is the energy average value of the second received signal in the second half symbol period in the N 2 symbol periods; the determining module 901 is used to determine the distributed antenna corresponding to the maximum average energy difference as first antenna.
  • the determination module 901 is configured to determine the product between the maximum average energy difference and the coefficient as the determination threshold.
  • An embodiment of the present application further provides an electronic label, the electronic label includes an integrated circuit, and the integrated circuit is used to implement the symbol detection method on the side of the electronic label in the embodiment of FIG. 4 or FIG. 5 .
  • Embodiments of the present application further provide a reader, which includes a programmable logic circuit and/or program instructions, and is used to implement symbol detection on the reader side in the embodiment of FIG. 4 or FIG. 5 when the reader is running method.
  • a reader which includes a programmable logic circuit and/or program instructions, and is used to implement symbol detection on the reader side in the embodiment of FIG. 4 or FIG. 5 when the reader is running method.
  • the embodiment of the present application also provides an environmental backscattering system, characterized in that the environmental backscattering system includes: an electronic tag and a reader, and the reader is equipped with a plurality of distributed antennas;
  • a reader for determining a first antenna of the plurality of distributed antennas
  • a reader configured to receive a first received signal through a first antenna, where the first received signal includes a second radio frequency signal obtained by backscattering the first radio frequency signal by the electronic tag according to the original symbol;
  • the reader is used to determine the original symbol corresponding to the first received signal.
  • the electronic tag is used to perform mark-reversal code encoding on the original symbol; the electronic tag is used to backscatter the first radio frequency signal according to the mark-reversed code-encoded original symbol.
  • the first received signal corresponds to N 1 symbol periods, and N 1 is a positive integer; for the ith symbol period in the N 1 symbol periods, the reader is configured to The relationship between the energy difference and the judgment threshold determines the original symbol corresponding to the first received signal in the ith symbol period; wherein, the energy difference is the signal energy value of the first received signal in the second half of the symbol period and the first half of the symbol period.
  • the energy difference between the signal energy values in symbol periods, i is a positive integer not greater than N 1 .
  • the reader when the absolute value of the energy difference is greater than the determination threshold, the reader is used to determine that the original symbol corresponding to the i-th symbol period of the first received signal is 0; When the value is less than the determination threshold, the reader is used to determine that the original symbol corresponding to the i-th symbol period of the first received signal is 1.
  • the signal energy value corresponding to the symbol 0 in the sign inversion code is smaller than the signal energy value corresponding to the symbol 1; when the energy difference value is a positive value and the energy difference value is greater than the judgment threshold, the reader, It is used to determine that the original symbol corresponding to the first received signal in the ith symbol period is 0; when the energy difference is negative and the absolute value of the energy difference is greater than the judgment threshold, the reader is used to determine the detection An error occurred.
  • the signal energy value corresponding to the symbol 0 in the sign inversion code is greater than the signal energy value corresponding to the symbol 1; in the case that the energy difference value is a negative value and the absolute value of the energy difference value is greater than the determination threshold, The reader is used to determine that the original symbol corresponding to the first received signal in the ith symbol period is 0; when the energy difference is positive and the energy difference is greater than the determination threshold, the reader is used to determine the detection An error occurred.
  • the reader is used to respectively receive the second received signal through a plurality of distributed antennas, the second received signal corresponds to N 2 symbol periods, and N 2 is a positive integer; the reader is used to determine the average energy difference value, the average energy difference is the absolute value of the difference between the first average energy and the second average energy, and the first average energy is the energy average of the second received signal in the first half of the N 2 symbol periods. value, the second average energy is the energy average value of the second received signal in the second half symbol period of the N 2 symbol periods; the reader is used to determine the distributed antenna corresponding to the largest average energy difference as the first an antenna.
  • a reader for determining the product between the largest average energy difference and the coefficient as the decision threshold.
  • the ambient backscattering system further includes: an ambient radio frequency signal source, and the first radio frequency signal is a signal sent by the ambient radio frequency signal source.
  • a computer-readable storage medium stores at least one instruction, at least one piece of program, code set or instruction set, at least one instruction, at least one piece of program, code set Or the instruction set is loaded and executed by the processor to implement the symbol detection method executed by the communication device provided by the above-mentioned various method embodiments.
  • a computer program product or computer program comprising computer instructions stored in a computer readable storage medium from which a processor of a computer device can Reading the storage medium reads the computer instructions, and the processor executes the computer instructions, so that the computer device executes the symbol detection method described in the above aspects.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

Un procédé et un appareil de détection de symbole, et un système, qui se rapportent au domaine des communications sans fil sont divulgués. Le procédé est appliqué à un lecteur, et le lecteur est pourvu d'une pluralité d'antennes distribuées. Le procédé consiste : à déterminer une première antenne parmi une pluralité d'antennes distribuées ; à recevoir un premier signal de réception au moyen de la première antenne, le premier signal de réception comprenant un second signal radiofréquence obtenu par rétrodiffusion d'un premier signal radiofréquence par une étiquette électronique selon un symbole d'origine ; et à déterminer le symbole d'origine correspondant au premier signal de réception.
PCT/CN2020/114855 2020-09-11 2020-09-11 Procédé et appareil de détection de symbole, et système WO2022052056A1 (fr)

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CN202080100080.1A CN115428365B (zh) 2020-09-11 2020-09-11 符号检测方法、装置及系统
PCT/CN2020/114855 WO2022052056A1 (fr) 2020-09-11 2020-09-11 Procédé et appareil de détection de symbole, et système

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