CN105187069A - Method using differential transmission and Manchester encoding to enhance backscatter - Google Patents
Method using differential transmission and Manchester encoding to enhance backscatter Download PDFInfo
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- CN105187069A CN105187069A CN201510581620.3A CN201510581620A CN105187069A CN 105187069 A CN105187069 A CN 105187069A CN 201510581620 A CN201510581620 A CN 201510581620A CN 105187069 A CN105187069 A CN 105187069A
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Abstract
The invention relates to an environmental backscattering method, in particular to a method using differential transmission and Manchester encoding to enhance backscatter. The method comprises the steps that: a transmitter and a receiver are constructed; the transmitter and the receiver store energy when impedances are matched; a signal is subjected to Manchester encoding when the impedances do not match, and the signal is transmitted through the transmitter and is received through the receiver; the receiver passes the received signal through an envelope detector, and then perform subtraction operation on the signal via a simulated subtracter to offset interference of the TV signal; an amplitude value of the signal obtained through subtraction operation is compared with a threshold value via a threshold value comparator, and transmitted information is decoded through a Manchester encoding rule. The method combines the differential transmission method and Manchester encoding method, can enhance environmental backscattering performance maximally, can effectively increase transmission distance by using Manchester codes, has suppression effect on interference in channels by adopting the differential transmission method, and reduces error rate of environmental backscattering.
Description
Technical field
The present invention relates to environment backscatter methods, be specially one and use differential transfer and Manchester's code to strengthen backscattered method.
Background technology
From the concept that mark Wei Saier formally proposes invisible calculating (InvisibleComputing), it is extensively interconnected that people are devoted to that thing and thing can be realized always, by the respondent behavior of complete wisdom, the degree of depth realizing people and thing merges, and launch a series of research and development, thus provide better service experience for the mankind for this reason.Past more than 20 year, although information physical merges this theory (Cyber-PhysicalSystem, CPS) extensively approved, the Internet of Things industry be connected towards all things on earth is also unanimously had an optimistic view of, but do not occur the extensive Internet of Things application of explosion type, the energy problem of Internet of things node of having to is one of them important bottleneck.
The cost that first energy problem result in Internet of Things application increases substantially.In fact, many biological environment supervisory control systems, Geological Disaster Warning System etc. all face a common problem, and that is difficult to maintain long-play exactly, directly results in the extensibility of this kind of resolving ideas and declining to a great extent of practicality.Naturally, people just expect, if node self is not equipped with or be not that the power-supply device mainly relying on self is powered, but support that it calculates by obtaining energy from environment, perception and communicate all right with networking.As far back as the passive label of radio-frequency (RF) identification (RadioFrequencyIDentification, RFID) of just favourable electromagnetic energy during the Second World War, this expansion being Radar Technology in civilian.2005, Intel Seattle researcher proposes label combining wireless charging technique, from the continuous wave of radio-frequency identification reader, obtain energy, have developed wireless identification and aware platform (WirelessIdentificationandSensingPlatform, WISP) new technology.2013, Washington, DC university designs environment backscattering prototype first, its main operation principle can obtain energy from the signals such as TV signal, WIFI signal, and communicated by this signal of backscattering, whether modulated process is by realizing impedance matching to realize, if impedance matching, the energy major part then transmitted is absorbed, the energy that recipient receives is less, if impedance mismatch, transmit leg is by signals reverse scattering, and the energy that recipient receives is more, can be realized transmission and the decoding of signal by the amount comparing receiving terminal.
Environment backscattering directly can obtain energy in existing environment, and the reader saved in conventional counter scattering RFID, achieve the communication between label, but due to this technology at the early-stage, so accessible communication distance is shorter, and in transmitting procedure, the error rate is higher.
Summary of the invention
The present invention, in order to solve the shorter problem higher with the error rate in transmitting procedure of environment backscatter communication distance, provides one and uses differential transfer and Manchester's code to strengthen backscattered method.
The present invention adopts following technical scheme to realize: a kind of use differential transfer and Manchester's code strengthen backscattered method, comprise the following steps:
Build environment backscattering device, comprise in it the transmitter and receiver that are integrated with power management module, it is the orthogonal poliarizing antenna of two polarised directions by the astronomical cycle on transmitter, antenna on receiver is also installed as the orthogonal poliarizing antenna of two polarised directions, and the polarised direction of polarised direction and transmitter poliarizing antenna is consistent, transmitter increases an inverter on original structure basis, and receiver comprises two envelope detectors, an analog subtracter and a threshold comparator;
Transmitter and receiver first adjust impedance matching condition separately, can obtain energy when impedance matching from TV signal, are stored in the capacitor of power management module in transmitter and receiver, provide energy for realizing communication;
Transmitter and receiver adjust impedance matching condition separately again, when impedance mismatch, information waiting for transmission is carried out Manchester's code by transmitter, pass through inverter again, information is overturn, forms two-way with same frequency and reversed-phase signal, then by two-way with same frequency and reversed-phase signal madulation in TV signal, the transmission of information can be carried out by backscattering TV signal, enter communications status; By using Manchester's code effectively can increase communication distance, and carrying synchronizing information due to Manchester's code, decreasing the step needing to do synchronous process to received signal, saving energy;
Two-way with same frequency and reversed-phase signal is transmitted respectively by the poliarizing antenna that two polarised directions of transmitter are contrary, two antennas of receiver receive the signal of correspondence direction respectively, and transmitter and receiver use polarised direction orthogonal two poliarizing antennas that two-way can be avoided to be interfered in transmitting procedure with signal frequently;
Two poliarizing antennas of receiver not only receive the two-way with same frequency and reversed-phase signal of transmission, can receive with TV signal frequently equally, then two paths of signals is carried out additive operation by analog subtracter by envelope detector, balance out the interference of TV signal, due to transmission is differential signal, pass through additive operation, double amplitude can be obtained, convenient decoding, using differential transfer and additive operation that less analogue device can be used to eliminate interference, reducing the error rate when ensureing equipment volume;
By the amplitude of signal that obtains after additive operation through threshold comparator compared with threshold value, and decoded the information of transmission by Manchester's code rule.
Differential transfer mode and Manchester's code two kinds of methods combine by the present invention, the backscattered performance of environment can be strengthened to greatest extent, use Manchester code effectively can increase environment backscatter transmission distance, utilize differential transfer mode to have good inhibitory action to the interference in channel, this also reduces the backscattered error rate of environment.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of differential transfer.
Fig. 2 is the design frame chart of differential transfer.
Fig. 3 is the oscillogram of Manchester's code.
In Fig. 1 and Fig. 2, Alice and Bod is two equipment not needing to install battery, two equipment all use double antenna, and the polarised direction of two antennas is orthogonal, at transmitting terminal signal waiting for transmission first through a signal inverter, then transmit on two antennas respectively, at receiving terminal end, subtraction is done to two paths of signals, then passing threshold comparison circuit decoded signal.
Embodiment
A kind of use differential transfer and Manchester's code strengthen backscattered method, comprise the following steps:
Build environment backscattering device, comprise in it the transmitter and receiver that are integrated with power management module, it is the orthogonal poliarizing antenna of two polarised directions by the astronomical cycle on transmitter, antenna on receiver is also installed as the orthogonal poliarizing antenna of two polarised directions, and the polarised direction of polarised direction and transmitter poliarizing antenna is consistent, transmitter increases an inverter on the original basis, and receiver comprises two envelope detectors, an analog subtracter and a threshold comparator;
Transmitter and receiver first adjust impedance matching condition separately, can obtain energy when impedance matching from TV signal, are stored in the capacitor of power management module in transmitter and receiver, provide energy for realizing communication;
Transmitter and receiver adjust impedance matching condition separately again, when impedance mismatch, information waiting for transmission is carried out Manchester's code by transmitter, pass through inverter again, information is overturn, forms two-way with same frequency and reversed-phase signal, then by two-way with same frequency and reversed-phase signal madulation in TV signal, the transmission of information can be carried out by backscattering TV signal, enter communications status;
Two-way with same frequency and reversed-phase signal is transmitted respectively by the poliarizing antenna that two polarised directions of transmitter are contrary, and two antennas of receiver receive the signal of correspondence direction respectively;
Two poliarizing antennas of receiver not only receive the two-way with same frequency and reversed-phase signal of transmission, can receive equally with TV signal frequently, then two paths of signals be carried out additive operation by analog subtracter by envelope detector, balances out the interference of TV signal;
By the amplitude of signal that obtains after additive operation through threshold comparator compared with threshold value, and decoded the information of transmission by Manchester's code rule.
In backscattered decode procedure, because antenna not only receives the signal of transmission, and directly can receive the TV signal, WIFI signal etc. that do not have to modulate, want the information of decodes transport, need the impact eliminating TV signal, WIFI signal etc., and consider the problem of energy consumption, need to use simple analogue device to realize.Existing solution mainly contains two kinds: a kind of method does average treatment to eliminate TV signal, WIFI signal to the signal received, but this method limit the speed of transmission, and signal can only transmit lower than under Mean Speed; Another kind method adopts double-antenna structure, because two antennas all can accept TV signal, division arithmetic is done to the signal that two antennas receive, can eliminate the interference of TV signal, this way does not limit speed, but the method needs to use a large amount of devices to realize division arithmetic, increase the volume of equipment, and carry out decoded signal by the size of the ratio obtained, because between ratio, gap is less, the accuracy rate using decoding is not very high.
The present invention is adopted differential transfer mode to carry out transmission information and is eliminated the interference of TV signal by simple subtraction.Differential transfer is exactly the transmitting terminal signal of telecommunication that transmission amplitude equal phase is contrary on two strip antennas, and receiving terminal, to two the signal subtraction accepted, obtains the double signal of amplitude like this.All comprise TV signal due in the two paths of signals that receives, by additive operation, the interference of TV signal can be eliminated, and subtraction just can be realized by simple device, reduces the volume of equipment.Due to by additive operation in the process of decoding, the amplitude of signal is double, just can decoded signal accurately by simple threshold circuit.Differential transfer also has very strong interference free performance, its jamproof principle is: if two signal line all receive the interference signal of (homophase, constant amplitude) equally, because receiving terminal is to the signal subtraction of two lines accepted, therefore interference signal is by basic neutralisation.
But differential transfer mode used in environment backscattering and have a problem to need to solve, differential transfer before is all used in the wired situation, and when wireless, on two antennas, transmission is with signal frequently, is easy to mutual interference in same channel.Two antennas of transmitting terminal and receiving terminal how are allowed to transmit data respectively and be not interfered? common solution is frequency division multiplexing or time division multiplexing, but because back-scattered signal all reflects TV signal, frequency is consistent, so frequency division multiplexing is unavailable, if use time-multiplexed words to need to store the data received, this is obviously irrational to environment backscattering.In order to address this problem, the present invention uses the antenna of different polarised direction to transmit, the linear polarization direction of two of transmitting terminal antennas is mutually vertical, and two reception antennas of signal receiving end are placed too, can realize non-interference between two antennas like this.
Suitable coded system is adopted effectively to increase communication distance and to reduce the error rate.But traditional encoding mechanism such as CDMA uses random sequence to carry out coded message, such as, byte 0 is represented by " 101110111 " sequence, byte 1 is represented by sequence " 111011011 ", but in decode procedure, receiving terminal needs do synchronous process to the signal received and carry out related calculation, but this can not realize in environment backscattering, and the energy shortage of absorption enough realizes relevant and synchronous calculating.Existing method uses orthogonal coding, this principle copies the orthogonality of cosine and sine signal, the periodic signal of similar cosine and sine signal is produced at output, such as: represent 1 with " 10101010 ", " 00000000 " represents 0, carrys out decoded information by calculating at receiving terminal the amount received, although change method not need synchronously to process information, but it needs multidigit information to represent an information, and this way still needs to carry out related calculation, this is waste energy beyond doubt.
In order to address this problem, Manchester's code is used in environment backscattering by the present invention first, and in Manchester's code, there is a saltus step centre of each, and the saltus step in the middle of position both made clock signal, date number again; Saltus step from low to high represents " 1 ", and saltus step from high to low represents " 0 ".Clock and packet contain in a stream by Manchester's code, while transmission code information, also clock sync signal is transferred to the other side together, in every coding, has a saltus step, there is not DC component, therefore there is self-synchronization and good interference free performance.Recipient utilizes the specific coding including synchronizing signal to extract synchronizing signal to lock the clock pulse frequency of oneself from signal self, reaches synchronous object.
Use Manchester's code to realize motor synchronizing, and only can represent a byte by the data in a time slot, the time that not only saves like this also saves energy, is best suited for environment backscattered.As shown in Figure 2, comprise Manchester's code and its reverse signal in figure, two paths of signals transmits Mancunian schematic diagram on the antenna of different polarised direction, by doing additive operation at receiving terminal, can reach double amplitude, and the accuracy rate of decoding increases.
Two kinds of methods combine and can strengthen the backscattered performance of environment to greatest extent, use Manchester code effectively can increase transmission range, utilize differential transfer mode to have good inhibitory action to the interference in channel, this also reduces the backscattered error rate of environment.
Claims (1)
1. use differential transfer and Manchester's code to strengthen a backscattered method, it is characterized in that comprising the following steps:
Build environment backscattering device, comprise in it the transmitter and receiver that are integrated with power management module, it is the orthogonal poliarizing antenna of two polarised directions by the astronomical cycle on transmitter, antenna on receiver is also installed as the orthogonal poliarizing antenna of two polarised directions, and the polarised direction of polarised direction and transmitter poliarizing antenna is consistent, transmitter increases an inverter on the original basis, and receiver comprises two envelope detectors, an analog subtracter and a threshold comparator;
Transmitter and receiver first adjust impedance matching condition separately, can obtain energy when impedance matching from TV signal, are stored in the capacitor of power management module in transmitter and receiver, provide energy for realizing communication;
Transmitter and receiver adjust impedance matching condition separately again, when impedance mismatch, information waiting for transmission is carried out Manchester's code by transmitter, pass through inverter again, information is overturn, forms two-way with same frequency and reversed-phase signal, then by two-way with same frequency and reversed-phase signal madulation in TV signal, the transmission of information can be carried out by backscattering TV signal, enter communications status;
Two-way with same frequency and reversed-phase signal is transmitted respectively by the poliarizing antenna that two polarised directions of transmitter are contrary, and two antennas of receiver receive the signal of correspondence direction respectively;
Two poliarizing antennas of receiver not only receive the two-way with same frequency and reversed-phase signal of transmission, can receive equally with TV signal frequently, then two paths of signals be carried out additive operation by analog subtracter by envelope detector, balances out the interference of TV signal;
By the amplitude of signal that obtains after additive operation through threshold comparator compared with threshold value, and decoded the information of transmission by Manchester's code rule.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107911193A (en) * | 2017-09-29 | 2018-04-13 | 浙江大学 | The symbol detection method of environment backscatter system based on Differential Manchester Encoding |
| CN108833316A (en) * | 2018-04-08 | 2018-11-16 | 中国船舶重工集团公司第七〇九研究所 | A kind of passive WiFi scatter communication method and system based on MCU microprocessor |
| CN109889236A (en) * | 2019-01-24 | 2019-06-14 | 西北大学 | For the joint coding method based on Alamouti coding of single Base-type backscatter communications |
| CN110266339A (en) * | 2019-05-06 | 2019-09-20 | 西安电子科技大学 | A kind of PNC decoding circuit for full duplex backscatter communications |
| CN112055951A (en) * | 2018-05-01 | 2020-12-08 | 华为技术有限公司 | Differential termination modulation for backchannel communications |
| CN113891424A (en) * | 2021-10-13 | 2022-01-04 | 东莞职业技术学院 | Method and equipment for assisting backscatter communication based on Internet of things node |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107911193A (en) * | 2017-09-29 | 2018-04-13 | 浙江大学 | The symbol detection method of environment backscatter system based on Differential Manchester Encoding |
| CN108833316A (en) * | 2018-04-08 | 2018-11-16 | 中国船舶重工集团公司第七〇九研究所 | A kind of passive WiFi scatter communication method and system based on MCU microprocessor |
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| CN112055951A (en) * | 2018-05-01 | 2020-12-08 | 华为技术有限公司 | Differential termination modulation for backchannel communications |
| CN109889236A (en) * | 2019-01-24 | 2019-06-14 | 西北大学 | For the joint coding method based on Alamouti coding of single Base-type backscatter communications |
| CN110266339A (en) * | 2019-05-06 | 2019-09-20 | 西安电子科技大学 | A kind of PNC decoding circuit for full duplex backscatter communications |
| CN110266339B (en) * | 2019-05-06 | 2020-08-11 | 西安电子科技大学 | PNC decoding circuit for full-duplex backscatter communication |
| CN113891424A (en) * | 2021-10-13 | 2022-01-04 | 东莞职业技术学院 | Method and equipment for assisting backscatter communication based on Internet of things node |
| CN113891424B (en) * | 2021-10-13 | 2023-08-18 | 东莞职业技术学院 | Method and equipment for assisting backscatter communication based on Internet of things node |
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