CN113676263B - Human body internal communication device and method based on ultrasonic backscattering - Google Patents
Human body internal communication device and method based on ultrasonic backscattering Download PDFInfo
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- CN113676263B CN113676263B CN202110910906.7A CN202110910906A CN113676263B CN 113676263 B CN113676263 B CN 113676263B CN 202110910906 A CN202110910906 A CN 202110910906A CN 113676263 B CN113676263 B CN 113676263B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
- H04B13/005—Transmission systems in which the medium consists of the human body
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
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- H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a human body communication device and method based on ultrasonic backscattering, wherein the method comprises the following steps: the sending module generates an inquiry signal, performs digital modulation and pulse forming on the inquiry signal to obtain an ultrasonic signal, and sends the ultrasonic signal through a piezoelectric material of the reader; the tag receives ultrasonic signals through piezoelectric materials, acquires human body information to obtain human body information bits, and maps the human body information bits into tag code sequences by orthogonal code sequences; performing energy collection and backscattering of the tag code sequence through an ultrasonic interrogation signal by controlling impedance matching of the piezoelectric material to obtain a backscattering signal; and the receiving module is used for matching, detecting and demapping the backscatter signals to obtain human body information bits. The invention utilizes the characteristics of piezoelectric materials to realize the ultra-low power consumption transmission of human body signals; by utilizing the balanced orthogonal code sequence, the multipath effect of the human body is effectively overcome, and the reliable ultrasonic in-vivo communication with ultra-low power consumption is realized.
Description
Technical Field
The invention relates to the technical field of ultrasonic communication and human body communication, in particular to a human body communication device and method based on ultrasonic backscattering.
Background
In recent years, the wireless medical technology is rapidly developed in the aspect of medical equipment, and the combination of the fifth generation and future mobile communication technology and intelligent sensing equipment is expected to realize real-time monitoring of various physiological signals of a human body, such as blood pressure, blood sugar, electrocardiosignals, electromyographic signals and the like; the wireless capsule endoscope and intelligent drug delivery can be realized by combining the medical intelligent Internet of things. The real-time and wide health monitoring has obvious research value for preventing and treating various chronic diseases, such as diabetes, epilepsy and the like, and can also relieve the medical monitoring problem facing the aging population.
At present, scientific research and industrial application mainly focus on wearable medical equipment, and the problems of discontinuous and inaccurate monitoring data caused by equipment damage and loss are faced; and the long-term wearing causes the problems of limited mobility, uncomfortable wearing and the like. With the development of the ultra-miniaturized technology and the generation of the nano-scale medical implantation equipment, the implantation medical equipment can realize real-time, continuous, accurate and long-term monitoring of human health data. Compared with radio frequency waves adopted by wireless communication, the radio frequency waves have the advantages that the signals are quickly attenuated in the in-vivo environment, the potential harm of long-term radiation is realized, the ultrasonic waves are widely applied to clinical treatment and diagnosis, and no harmful side effect is generated on human bodies. Therefore, the adoption of ultrasound for wireless intra-body communication of medical implants is a reliable solution for the realization of the future medical internet of things.
Intra-body ultrasound communication must meet power and device size limitations to avoid excessive thermal injury to body tissues and surgical implant risks. The size of a wireless communication device is primarily affected by various active devices, such as waveform generators, amplifiers, microprocessors, and the like. The backscattering communication is firstly applied to radio frequency identification, a reader sends an inquiry signal, a tag is used as a passive device to carry out backscattering communication on the inquiry signal of the reader, and the inquiry signal of the reader is used as a carrier to transmit information collected by the tag. Backscatter communications can enable ultra-low power micro-tags by eliminating active devices. However, since the reader interrogation signal needs to be transmitted through a dual path of "reader-tag-reader", the signal attenuation is more severe than that of conventional one-way communication. The existing radio frequency backscattering communication technology also faces the problem that radio frequency signals are further seriously attenuated in a human body, and cannot be suitable for communication in the human body. In addition, various organs and tissues exist in the human body, and the scattered signals generated by the multipath effect cause serious interference to the backscatter signals of the tags.
Disclosure of Invention
In order to solve the defects of the prior art and realize reliable ultrasonic wave human body internal communication with low power consumption, the invention provides a human body internal communication device and a method based on ultrasonic wave backscattering, the method carries out backscattering communication through impedance matching of piezoelectric materials of a tag, and the ultra-miniature tag is used for collecting and transmitting signals in a human body; the information bit mapping unit of the label is utilized to carry out code mapping on the human body information bits, and the signal-to-noise ratio of the signal is improved by increasing the length of the code sequence, thereby effectively overcoming signal attenuation; meanwhile, as the label code sequence is a balanced orthogonal code sequence, the interference generated by other scattering signals is effectively overcome.
A first object of the present invention is to provide an intra-body communication device based on ultrasonic backscatter.
A second object of the present invention is to provide an intra-body communication method based on ultrasonic backscatter.
The first purpose of the invention can be achieved by adopting the following technical scheme:
a transmitting module for generating an ultrasonic interrogation signal;
the tag is used for acquiring human body information, receiving the ultrasonic inquiry signal and performing backscattering on the human body information through the ultrasonic inquiry signal to obtain a backscattering signal;
the receiving module is used for receiving the backscattering signals and matching, detecting and demapping the backscattering signals to obtain human body information bits;
the ultrasonic interrogation signal and the backscatter signal are both ultrasonic signals;
the reader and the tag are both located in a wireless communication network using a human body as a transmission medium, and both transmit and receive ultrasonic signals through respective piezoelectric materials.
Further, the sending module comprises an interrogation signal generating unit, a digital modulation unit and a signal shaping unit, wherein:
the interrogation signal generating unit is used for generating an interrogation bit sequence;
the digital modulation unit is used for digitally modulating the inquiry bit sequence to generate a reader code sequence;
the signal forming unit is used for carrying out signal forming on the reader code sequence to obtain an ultrasonic inquiry signal and controlling a piezoelectric material of the reader to send the ultrasonic inquiry signal;
the piezoelectric material of the tag receives the ultrasonic interrogation signal;
the label comprises a human body information acquisition unit, an information bit mapping unit, a backscattering communication unit and an energy collection unit, wherein:
the human body information acquisition unit is used for acquiring human body information to obtain human body information bits;
the information bit mapping unit is used for mapping the human body information bits into a tag code sequence of a tag code book;
the backscattering communication unit is used for backscattering the tag code sequence of the tag code book through the ultrasonic interrogation signal according to impedance matching of the piezoelectric material of the tag to obtain a backscattering signal;
the energy collection unit is used for collecting the ultrasonic interrogation signal so as to control the impedance matching of the piezoelectric material of the tag;
receiving the backscatter signal by a piezoelectric material of the reader;
the receiving module comprises a matching unit, a detecting unit and a demapping unit, wherein:
the matching unit is used for matching the backscatter signal with the reader code sequence and all tag code sequences in the tag code book to obtain a matching signal;
the detection unit is used for detecting the matching signal to obtain an estimated tag code sequence;
the demapping unit is configured to map the estimated tag decoding sequence into human body information bits;
the ultrasonic signal is an ultrasonic pulse signal or an ultrasonic continuous wave signal.
Further, the energy collection unit is a passive energy storage circuit or an active energy storage circuit.
The second purpose of the invention can be achieved by adopting the following technical scheme:
generating an ultrasonic interrogation signal by a transmission module;
the tag collects human body information and receives the ultrasonic interrogation signal, and backscatters the human body information through the ultrasonic interrogation signal to obtain a backscattering signal;
and the receiving module receives the backscattering signal and performs matching, detection and demapping on the backscattering signal to obtain a human body information bit.
Further, the generating an ultrasonic interrogation signal by the sending module specifically includes:
generating, by an interrogation signal generation unit, an interrogation bit sequence;
performing digital modulation on the inquiry bit sequence through a digital modulation unit to generate a reader code sequence;
performing signal shaping on the reader code sequence through a signal shaping unit to obtain an ultrasonic wave inquiry signal; and controlling the piezoelectric material of the reader to send the ultrasonic interrogation signal;
the tag collects human body information and receives the ultrasonic interrogation signal, and backscatters the human body information through the ultrasonic interrogation signal to obtain a backscattering signal, and the method specifically comprises the following steps:
acquiring human body information through a human body information acquisition unit to obtain human body information bits;
mapping the human body information bit into a tag code sequence of a tag code book through an information bit mapping unit;
receiving the ultrasonic interrogation signal through the piezoelectric material of the tag;
and backscattering the tag code sequence of the tag code book through the ultrasonic interrogation signal according to the impedance matching of the piezoelectric material of the tag through a backscattering communication unit to obtain a backscattering signal.
Further, the mapping the human body information bits into a tag code sequence of a tag code book by an information bit mapping unit specifically includes:
mapping the human body information bit into a kth label code sequence a of a label code book a by an information bit mapping unit k ；
Wherein k =1 bc The label codebook a has N bc A sequence of tag codes, N bc Is a positive integer greater than 1; the length of each label code sequence is a set threshold value N f ，N f Is a positive integer greater than 1; the tag code sequence is an orthogonal code sequence;
the backscatter communication unit backscatters the tag code sequence of the tag codebook through the ultrasonic interrogation signal according to impedance matching of a piezoelectric material of the tag, so as to obtain a backscatter signal, and specifically includes:
according to impedance matching of the piezoelectric material of the tag, if backscattering is not performed, collecting the ultrasonic interrogation signal to an energy collection unit; otherwise, performing backscattering on the tag code sequence of the tag code book through the ultrasonic interrogation signal to obtain a backscattering signal;
the backscattering is achieved by controlling the impedance matching of the piezoelectric material of the tag by an energy harvesting unit to change the phase, amplitude or position of the backscattering of the ultrasonic interrogation signal.
Further, the orthogonal code sequence is a balanced orthogonal code sequence a m And is made of
Wherein, a m The mth tag code sequence of the tag codebook a, a m,j Sequence of tag codes a for a tag codebook m The jth element of (1).
Further, the receiving module receives the backscatter signal, and performs matching, detection, and demapping on the backscatter signal to obtain a human body information bit, which specifically includes:
receiving a backscatter signal through a piezoelectric material of the reader; the backscattering signals comprise backscattering signals and interference signals sent by the tags;
matching the backscatter signal with the reader code sequence and all tag code sequences in the tag code book by a matching unit to obtain a matching signal;
detecting the matching signal through a detection unit to obtain an estimated tag code sequence;
mapping the estimated tag decoding sequence into human body information bits through a demapping unit.
Further, the detecting unit detects the matching signal to obtain an estimated tag code sequence, specifically:
and detecting the matching signal through a detection unit, judging and selecting the maximum detection value, and taking the tag code sequence corresponding to the maximum detection value as an estimated tag code sequence.
Further, the detection is coherent detection, incoherent detection or the detection is performed by combining coherent detection and incoherent detection;
the judgment criterion adopted by the judgment is a maximum likelihood criterion or a maximum posterior probability criterion.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts ultrasonic signals to realize low attenuation of signal transmission in human body.
2. The invention carries out backscattering communication through impedance matching of the piezoelectric material of the tag, does not need active devices such as a signal generator, an amplifier and the like, can realize that the ultra-miniaturized tag is used for collecting and transmitting signals in a human body, and overcomes the damage of surgical implantation to human tissues.
3. The invention carries out code mapping on the human body information bit through the information bit mapping unit of the label, and improves the signal-to-noise ratio of the signal by increasing the length of the code sequence, thereby effectively overcoming the signal attenuation; because the label code sequence is adopted as the balanced orthogonal code, the interference generated by other scattering signals can be effectively overcome, and the reliable ultrasonic in-vivo communication with low power consumption is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an intra-body communication device based on ultrasonic backscattering according to an embodiment of the present invention.
Fig. 2 is a flowchart of an intra-body communication method based on ultrasonic backscatter according to an embodiment of the present invention.
Fig. 3 is a process diagram of an intra-body communication method based on ultrasonic backscattering according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention. It should be understood that the description of the specific embodiments is intended to be illustrative only and is not intended to be limiting. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example (b):
as shown in fig. 1, the present embodiment provides an intra-human body communication device based on ultrasonic backscattering, which includes a reader and a tag, where the reader includes a transmitting module and a receiving module, where:
the sending module comprises an inquiry signal generating unit, a digital modulation unit and a signal shaping unit, wherein:
an interrogation signal generation unit for generating an interrogation bit sequence;
the digital modulation unit is used for carrying out digital modulation on the inquiry bit sequence to generate a reader code sequence;
and the signal shaping unit is used for carrying out signal shaping on the reader code sequence to obtain an ultrasonic inquiry signal and controlling the piezoelectric material of the reader to send the ultrasonic inquiry signal.
The piezoelectric material of label receives ultrasonic interrogation signal, and the label includes human information acquisition unit, information bit mapping unit, backscatter communication unit and energy collection unit, wherein:
the human body information acquisition unit is used for acquiring human body information to obtain human body information bits;
the human body information acquisition unit can be equipment with an acquisition function, and the human body information comprises data such as blood sugar and blood pressure.
An information bit mapping unit for mapping the human body information bit into a tag code sequence of a tag code book;
the backscattering communication unit is used for backscattering the tag code sequence through an ultrasonic wave inquiry signal according to the impedance matching of the piezoelectric material of the tag to obtain a backscattering signal;
if the backscattering is not carried out, collecting the ultrasonic inquiry signal to an energy collecting unit;
and if backscattering is carried out, backscattering is carried out on the tag code sequence through the ultrasonic interrogation signal, and a backscattering signal is obtained.
An energy harvesting unit for harvesting the ultrasonic interrogation signal to control backscatter communications of the tag;
the tag stores energy through an energy harvesting unit to control impedance matching of the piezoelectric material of the tag, thereby backscattering the signal.
The energy collection unit is a passive energy storage circuit or an active energy storage circuit.
In this embodiment, the energy harvesting unit is an active energy storage circuit, and energy harvesting is not required.
The piezoelectric material of reader receives the backscatter signal, and the receiving module includes matching unit, detecting element and demapping unit, wherein:
a matching unit for matching the backscatter signal with a reader code sequence and a different tag code sequence;
the detection unit is used for detecting and judging the label code sequence corresponding to the maximum matching value;
and the demapping unit is used for mapping the label decoding sequence corresponding to the maximum matching value into the human body information bit.
The ultrasonic interrogation signal and the backscatter signal are both ultrasonic signals.
In this embodiment, the reader and the tag are both located in a wireless communication network that uses a human body as a transmission medium, and both send and receive ultrasonic signals through a piezoelectric material.
The ultrasonic signal is an ultrasonic pulse signal or an ultrasonic continuous wave signal.
The human body communication device provided by the embodiment has a simple structure, and can be used for realizing ultra-miniature low-power-consumption ultrasonic human body communication.
As shown in fig. 2 and fig. 3, the present embodiment further provides an intra-body communication method based on ultrasonic backscattering, which is applied to the intra-body communication system of the intra-body communication device, and specifically includes the following steps:
s201, generating an ultrasonic inquiry signal through a sending module.
Further, step S201 specifically includes:
(1) Generating a length N by an interrogation signal generating unit f Each bit having a value of {0,1}.
(2) Digitally modulating the interrogation bit sequence by a digital modulation unit to produce a length N f The value of the element in the reader code sequence d, d is {1, -1}.
The digital modulation is pulse phase modulation, pulse amplitude modulation, pulse position modulation or pulse waveform modulation.
In this embodiment, the digital modulation is pulse phase modulation, and the length of the reader bit sequence is N f With a value of 4, the challenge bit sequence is [ 10 ]]The reader code sequence d is [ 1-1]。
(3) And the signal forming unit is used for carrying out signal forming on the reader code sequence to obtain an ultrasonic inquiry signal and controlling the piezoelectric material of the reader to send the ultrasonic inquiry signal.
The ultrasonic interrogation signal s (t) is:
where t is time, τ i For initiating transmission of signalsTime, j being the sequence number of the transmission time frame, d j For the jth element in the reader code sequence d, p (t) is a monocycle pulse signal, and the pulse width of p (t) is smaller than the width of a time frame; t is a unit of f Is the time length of one time frame.
In this example,. Tau. i The value is 0.
S202, the tag collects human body information and receives ultrasonic inquiry signals, and backscattering the human body information through the ultrasonic inquiry signals to obtain backscattering signals.
Collecting human body signals and mapping human body information bits; the ultrasonic wave receiving device is used for receiving the ultrasonic wave inquiry signal and backscattering the ultrasonic wave inquiry signal to obtain a backscattering signal;
further, step S202 specifically includes:
(1) And collecting the human body information through a human body information collecting unit to obtain human body information bits.
(2) Mapping human body information bits into a tag code sequence a of a tag code book by an information bit mapping unit k 。
An information bit mapping unit maps the human body information bits into a kth tag code sequence a of a tag code book a k Wherein k =1 bc (ii) a The label codebook has N bc A sequence of tag codes, each sequence of tag codes having a length N f (ii) a Each tag code sequence is an orthogonal code sequence and can be generated by a Hadamard matrix and a Walsh matrix.
Preferably, the orthogonal code sequence is a balanced orthogonal code sequence, and
a k,j sequence of tag codes a for a tag codebook k The jth element of (1); balanced orthogonal code sequences have the same number of "+1" and "-1"; the number of bits of the human body information carried by a label code sequence is
The number of the main components is one,
is a rounded down function.
In this embodiment, the tag code book a has 2 orthogonal tag code sequences with a length of 4, and one code sequence carries 1 human body information bit; the orthogonal code sequence is generated by a Hadamard matrix, which is a 1 ＝[1 -1 1 -1]，a 2 ＝[1 1 -1 -1](ii) a Mapping human body information bit '0' into label code sequence a of label code book 1 Bit "1" is mapped to a tag code sequence a of a tag codebook 2 。
Human body information bits transmitted by the balanced orthogonal code mapping label are utilized, human body multipath effect is effectively overcome, and reliable ultrasonic in-vivo communication with ultra-low power consumption is achieved.
(3) An ultrasonic interrogation signal s (t) is received through the piezoelectric material of the tag.
(4) And backscattering the label code sequence of the label code book through the ultrasonic interrogation signal according to the impedance matching of the piezoelectric material of the label through a backscattering communication unit to obtain a backscattering signal.
The backscatter signal is:
where α is the attenuation coefficient of the signal transmitted from the reader to the tag, a k,j Sequence of tag codes a for a tag code book k J element of (2), d j For the jth element in the reader code sequence d, p (t) is a monocycle signal, n 0 (t) is the reader-to-tag channel noise.
The implementation principle of backscatter communication is that the tag changes the phase, amplitude or position of ultrasonic interrogation signal backscatter by controlling impedance matching of piezoelectric material, and specifically includes:
when the impedance matching circuit is short-circuited, the piezoelectric material of the tag backscatters the ultrasonic interrogation signal;
when the impedance matching circuit is open-circuited, the piezoelectric material of the tag performs 180-degree inversion and backscattering on the ultrasonic interrogation signal;
when the impedance matching circuit is provided with a time delay circuit, the piezoelectric material of the label carries out backscattering after delaying the ultrasonic interrogation signal;
when the impedance matching circuit has adjustable impedance, the impedance is controlled to control the signal amplitude of the ultrasonic interrogation signal which is backscattered by the tag piezoelectric material, when the impedance is matched with the piezoelectric material of the tag, the ultrasonic interrogation signal is absorbed by the tag piezoelectric material, and the ultrasonic interrogation signal is collected by the energy collection unit of the tag without backscattering.
Specifically, the principle of backscatter communication is that the tag changes the phase of the backscatter of the reader interrogation signal by controlling the impedance matching of the piezoelectric material:
when transmitting tag code sequence element a k,j When the signal is + 1', the impedance matching circuit is short-circuited, and the piezoelectric material of the tag backscatters the ultrasonic interrogation signal;
when transmitting tag code sequence element a k,j At "-1", the impedance matching circuit is open and the piezoelectric material of the tag inverts 180 degrees to the ultrasonic interrogation signal and backscatters.
When the tag does not send signals, the impedance of the impedance matching circuit is matched with the piezoelectric material of the tag, the piezoelectric material of the tag absorbs the ultrasonic interrogation signals, and the energy collection unit of the tag collects energy without backscattering.
The embodiment utilizes the characteristics of the piezoelectric material, realizes that the ultra-low power consumption label is used for ultrasonic backscattering communication to transmit human body signals, and effectively avoids the problem of high power consumption of an active device applied to ultrasonic in-vivo communication.
And S203, the receiving module receives the backscatter signal, and performs matching, detection and demapping on the backscatter signal to obtain a human body information bit.
Further, step S203 specifically includes:
(1) The backscatter signal is received by a piezoelectric material of the reader.
The backscatter signals received by the piezoelectric material of the reader include backscatter signals transmitted by the tags and other interfering signals.
The backscatter signal received by the receiving module is:
wherein alpha is 2 For a signal to experience a "reader-tag-reader" dual path attenuation coefficient, a k,j Sequence of tag codes a for a tag codebook k J element of (2), d j For the jth element in the reader code sequence d, p (t) is a monocycle signal, β 2 The fading coefficient of the interference signal which is back scattered by other interferents in the human body, including organs and particles, and n (t) is the channel noise of the reader-tag-reader.
(2) And matching the backscatter signal with the reader code sequence and all tag code sequences in the tag code book by a matching unit to obtain a matching signal.
The matching unit matches the backscatter signal with all tag code sequences in the reader code sequence d and the tag code book a, and a matching signal generated with the mth tag code sequence is as follows:
wherein, a m M =1,2 for the mth tag code sequence of tag codebook a; d is a reader code sequence; alpha is alpha 2 The signal experiences the dual path attenuation coefficient of reader-tag-reader; a is k,j Sequence of tag codes a for a tag codebook k The jth element of (1); a is m,j Sequence of tag codes a for a tag code book m The jth element of (1); beta is a beta 2 The fading coefficient of the interference signal is that the signal is back-scattered by other interferents in the human body, including organs, particles and the like; d j Is the j element in the reader code sequence d; p (t) is a monocycle signal; n (t) is channel noise of reader-tag-reader; y is m1 (t) is a tag signal，y m2 (t) is an interference signal, n m (t) is a noise signal.
Due to a m Is a balanced orthogonal code sequence and
thereby matching the interference signal y in the signal m2 (t) =0, so the interference signal can be effectively overcome by adopting the balanced orthogonal code.
(3) And detecting the matching signal through a detection unit to obtain an estimated tag code sequence.
The detection mode can be coherent detection, non-coherent detection or detection combining coherent detection and non-coherent detection.
Preferably, in this embodiment, the detection method is non-coherent detection.
(3-1) the detection unit performs incoherent detection on the matching signal, wherein the detection signal is as follows:
wherein m =1,2,y m1 (t) is a label signal, n m (T) is a noise signal, T f Is the time length of one time frame.
And (3-2) judging and selecting a detection maximum value, and taking a label code sequence corresponding to the maximum detection value as an estimated label code sequence.
The decision criterion used is a maximum likelihood criterion or a maximum a posteriori probability criterion.
Preferably, the decision criterion adopted in this embodiment is a maximum likelihood criterion, and the formula is as follows:
wherein the content of the first and second substances,
is an estimated tag code sequence.
(4) The estimated tag code sequence is sequence mapped to human body information bits by a demapping unit.
Mapping the estimated tag code sequence into human body information bits, specifically comprising:
when the maximum energy is J 1 The estimated tag code sequence is
Demapping to obtain a human body information bit of '0';
when the maximum energy is J 2 The estimated tag code sequence is
The demapping obtains that the human body information bit is '1'.
Therefore, the method can overcome multipath interference in the human body, correctly recover the human body information bits acquired by the tags and realize low-power consumption human body communication.
Those skilled in the art will appreciate that all or part of the steps in the method for implementing the above embodiments may be implemented by a program to instruct related hardware, and the corresponding program may be stored in a computer readable storage medium.
It should be noted that although the method operations of the above-described embodiments are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the illustrated operations must be performed, to achieve desirable results. Rather, the depicted steps may change the order of execution. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.
In summary, the invention generates the interrogation signal through the sending module of the reader, and generates the ultrasonic signal after the interrogation signal is subjected to digital modulation and pulse forming in sequence, and sends the ultrasonic signal through the piezoelectric material of the reader; the method comprises the following steps that a tag collects human body information, receives ultrasonic signals through piezoelectric materials of the tag, obtains human body information bits through the human body information, and maps the human body information bits into tag code sequences of a tag code book through orthogonal code sequences; the tag collects energy by controlling impedance matching of the piezoelectric material and performs backscattering on a tag code sequence of a tag code book through an ultrasonic interrogation signal to obtain a backscattering signal; and a receiving module of the reader sequentially performs orthogonal code matching, detection and demapping on the backscatter signals to recover the human body information bits transmitted by the tag. The invention utilizes the characteristics of the piezoelectric material to realize that the ultra-low power consumption label is used for ultrasonic backscattering communication to transmit human body signals, thereby effectively avoiding the problem of high power consumption of an active device applied to ultrasonic in-vivo communication; human body information bits transmitted by the balanced orthogonal code mapping label are utilized, the human body multipath effect is effectively overcome, and reliable ultrasonic in-vivo communication with ultra-low power consumption is realized.
The above description is only for the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the scope of the present invention.
Claims (10)
1. An in-body communication device based on ultrasonic backscattering, characterized in that the device comprises a reader and a tag, the reader comprises a transmitting module and a receiving module, wherein:
a transmitting module for generating an ultrasonic interrogation signal;
the tag is used for acquiring human body information, receiving the ultrasonic inquiry signal and performing backscattering on the human body information through the ultrasonic inquiry signal to obtain a backscattering signal;
the receiving module is used for receiving the backscattering signals and matching, detecting and demapping the backscattering signals to obtain human body information bits;
the ultrasonic interrogation signal is received by a piezoelectric material of the tag, the tag comprises a human body information acquisition unit, an information bit mapping unit, a backscattering communication unit and an energy collection unit, and the human body information acquisition unit is used for acquiring human body information and obtaining human body information bits; the information bit mapping unit is used for mapping the human body information bits into a tag code sequence of a tag code book; the backscattering communication unit is used for backscattering the tag code sequence of the tag code book through the ultrasonic interrogation signal according to impedance matching of the piezoelectric material of the tag to obtain a backscattering signal; the energy harvesting unit is used for harvesting the ultrasonic interrogation signal so as to control impedance matching of a piezoelectric material of the tag; wherein the label code sequence is a balanced orthogonal code;
the ultrasonic interrogation signal and the backscatter signal are both ultrasonic signals;
the reader and the tag are both located in a wireless communication network using a human body as a transmission medium, and both transmit and receive ultrasonic signals through respective piezoelectric materials.
2. The in-human body communication device according to claim 1, wherein the transmission module comprises an interrogation signal generation unit, a digital modulation unit, and a signal shaping unit, wherein:
the interrogation signal generation unit is used for generating an interrogation bit sequence;
the digital modulation unit is used for digitally modulating the inquiry bit sequence to generate a reader code sequence;
the signal forming unit is used for carrying out signal forming on the reader code sequence to obtain an ultrasonic inquiry signal and controlling a piezoelectric material of the reader to send the ultrasonic inquiry signal;
receiving the backscatter signal by a piezoelectric material of the reader;
the receiving module comprises a matching unit, a detecting unit and a demapping unit, wherein:
the matching unit is used for matching the backscatter signal with the reader code sequence and all the tag code sequences in the tag code book to obtain a matching signal;
the detection unit is used for detecting the matching signal to obtain an estimated tag code sequence;
the demapping unit is configured to map the estimated tag decoding sequence into human body information bits;
the ultrasonic signal is an ultrasonic pulse signal or an ultrasonic continuous wave signal.
3. The intra-human body communication device according to claim 2, wherein the energy harvesting unit is a passive energy storage circuit or an active energy storage circuit.
4. An intra-body communication method based on ultrasonic backscattering, which is realized based on the device of any one of claims 1-3, and is characterized in that the method comprises the following steps:
generating an ultrasonic interrogation signal by a transmission module;
the tag collects human body information and receives the ultrasonic interrogation signal, and backscatters the human body information through the ultrasonic interrogation signal to obtain a backscattering signal;
and the receiving module receives the backscattering signal and performs matching, detection and demapping on the backscattering signal to obtain a human body information bit.
5. The method according to claim 4, wherein the generating of the ultrasonic interrogation signal by the transmitting module specifically comprises:
generating, by an interrogation signal generation unit, an interrogation bit sequence;
performing digital modulation on the inquiry bit sequence through a digital modulation unit to generate a reader code sequence;
performing signal forming on the reader code sequence through a signal forming unit to obtain an ultrasonic inquiry signal; and controlling the piezoelectric material of the reader to send the ultrasonic interrogation signal;
the tag collects human body information and receives the ultrasonic interrogation signal, and carries out backscattering on the human body information through the ultrasonic interrogation signal to obtain a backscattering signal, and the method specifically comprises the following steps:
acquiring human body information through a human body information acquisition unit to obtain human body information bits;
mapping the human body information bit into a tag code sequence of a tag code book through an information bit mapping unit;
receiving the ultrasonic interrogation signal through the piezoelectric material of the tag;
and backscattering the tag code sequence of the tag code book through the ultrasonic interrogation signal according to the impedance matching of the piezoelectric material of the tag through a backscattering communication unit to obtain a backscattering signal.
6. The method according to claim 5, wherein said mapping the human body information bits into a tag code sequence of a tag codebook by an information bit mapping unit specifically comprises:
mapping the human body information bit into a kth label code sequence a of a label code book a by an information bit mapping unit k ；
Wherein k =1 bc The label codebook a has N in common bc A sequence of tag codes, N bc Is a positive integer greater than 1; the length of each label code sequence is a set threshold value N f ，N f Is a positive integer greater than 1;
the backscatter communication unit backscatters the tag code sequence of the tag codebook through the ultrasonic interrogation signal according to impedance matching of a piezoelectric material of the tag, so as to obtain a backscatter signal, and specifically includes:
according to impedance matching of the piezoelectric material of the tag, if backscattering is not performed, collecting the ultrasonic interrogation signal to an energy collection unit; otherwise, performing backscattering on the tag code sequence of the tag code book through an ultrasonic inquiry signal to obtain a backscattering signal;
the backscattering is achieved by controlling the impedance matching of the piezoelectric material of the tag by an energy harvesting unit to change the phase, amplitude or position of the backscattering of the ultrasonic interrogation signal.
7. The method according to claim 4, wherein the balanced orthogonal code sequence is a m And is and
wherein, a m The mth tag code sequence of the tag codebook a, a m,j Sequence of tag codes a for a tag codebook m The jth element of (1).
8. The method according to claim 5, wherein the receiving module receives the backscatter signal, and performs matching, detection, and demapping on the backscatter signal to obtain a human body information bit, specifically comprising:
receiving a backscatter signal through a piezoelectric material of the reader; the backscatter signals comprise backscatter signals and interference signals sent by the tags;
matching the backscatter signal with the reader code sequence and all tag code sequences in the tag code book by a matching unit to obtain a matching signal;
detecting the matching signal through a detection unit to obtain an estimated tag code sequence;
mapping the estimated tag decoding sequence into human body information bits through a demapping unit.
9. The method according to claim 8, wherein said detecting said matching signal by a detecting unit to obtain an estimated tag code sequence comprises:
and detecting the matching signal through a detection unit, judging and selecting the maximum detection value, and taking the tag code sequence corresponding to the maximum detection value as an estimated tag code sequence.
10. The intra-human-body communication method according to claim 9, wherein the detection is coherent detection, non-coherent detection, or a combination of coherent detection and non-coherent detection;
the judgment criterion adopted by the judgment is a maximum likelihood criterion or a maximum posterior probability criterion.
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