CN111726143B - A wireless body area network communication system - Google Patents

Abstract

Embodiments of the present invention provide a wireless body area network communication system. The system includes: a transmitting end and a receiving end; the receiving end includes: a load resistance, a numerical control inductance array and a compensation inductance value calculator; the load resistance and the numerical control inductance array are connected in series between the signal electrode and the ground electrode in sequence, and the compensation inductance value calculator is connected to the load. The resistor is connected in parallel with the numerical control inductance array; the load resistance is used to generate a voltage signal according to the excitation signal emitted by the transmitter; the compensation inductance value calculator is used to calculate the compensation inductance value according to the voltage signal; the numerical control inductance array is used to calculate the compensation inductance value according to the compensation Inductance value, several inductances are determined from the multiple inductances of the numerically controlled inductance array as compensation inductances, and the reverse path loss in the wireless body area network communication system is compensated by the compensation inductances. The system provided by the embodiment of the present invention can dynamically and effectively compensate the reverse path loss in the system during the change of the human body posture, so that the power consumption of the system is greatly reduced.

Description

A wireless body area network communication system

technical field

Embodiments of the present invention relate to the technical field of wireless body area networks, and in particular, to a wireless body area network communication system.

Background technique

A wireless body area network (WBAN) refers to an information network established between electronic devices carried by individuals. In order to promote the development of wireless body area network, the wireless body area network standard IEEE802.15.6 was formally established in 2012. The standard specifies three types of signal frequency bands for wireless body area network communication: narrowband (narrowband, NB), ultra wideband (ultra wideband, UWB) and human body communication (human body communication, HBC) frequency bands. Among them, both narrowband and ultra-wideband are radio frequency communication methods, while human body communication is a non-radio frequency communication method, which regards the human body as a conductor and uses the human body as a channel to complete signal transmission. Compared with the way of radio frequency communication, human body communication is expected to realize the low power consumption and miniaturization of wireless body area network because it utilizes the characteristics of low loss of human body and does not need antennas and coils.

For the wireless body area network communication system based on human body communication, according to the different coupling methods, it can be divided into a wireless body area network communication system based on capacitive coupling and a wireless body area network communication system based on current coupling. Among them, the wireless body area network communication system based on capacitive coupling establishes a communication loop by capacitively coupling the two electrodes at the transmitting end or the receiving end with the human body and the air, thereby realizing signal conduction.

FIG. 1 is a schematic structural diagram of a wireless body area network communication system in the prior art. As shown in FIG. 1 , the system is a wireless body area network communication system based on capacitive coupling, including a transmitter and a receiver, wherein the transmitter includes a The signal electrode SE _tx , an AC signal source and a ground electrode GE _tx , and the receiving end includes a signal electrode SE _rx and a ground electrode GE _rx . Among them, the signal electrode SE _tx and the signal electrode SE _rx are both attached to the surface of the human body. At this time, a forward path is formed between the signal electrode SE _tx - the human body - the signal electrode SE _rx , and the ground electrode GE _tx - Air - ground electrode GE _rx constitutes the reverse path. Since the conductivity of the coupling capacitor in the air is much lower than that of the human body, the reverse path loss is much higher than the forward path loss.

In order to keep the low power consumption of the wireless body area network communication system, the reverse path loss needs to be compensated. Fig. 2 is a schematic structural diagram of a wireless body area network communication system with compensation function in the prior art. As shown in Fig. 2, a fixed inductance is usually connected in series between the signal electrode SE _rx and the ground electrode GE _rx at the receiving end to realize the Reverse path loss is compensated. However, the reverse path loss varies with the change of the posture of the human body, and the prior art cannot effectively compensate the reverse path loss during the dynamic change of the human posture, so the low power consumption of the system cannot be maintained. Therefore, it is an urgent problem to propose a wireless body area network communication system that can effectively compensate the reverse path loss during the dynamic change of the human body posture.

SUMMARY OF THE INVENTION

In view of the technical problems existing in the prior art, embodiments of the present invention provide a wireless body area network communication system.

In a first aspect, an embodiment of the present invention provides a wireless body area network communication system, including: a transmitter and a receiver; wherein the receiver includes:

Load resistors, digitally controlled inductor arrays, and compensated inductor value calculators; where,

The load resistor and the digitally controlled inductor array are connected in series between the signal electrode and the ground electrode in sequence, and the compensation inductance value calculator is connected in parallel with the load resistor and the digitally controlled inductor array;

The load resistor is used to generate a voltage signal according to the excitation signal emitted by the transmitting end;

the compensation inductance value calculator, used for calculating the compensation inductance value according to the voltage signal;

The digitally controlled inductance array is configured to determine a number of inductances from a plurality of inductances of the digitally controlled inductance array as compensation inductances according to the compensation inductance value, and use the compensation inductance to counteract the feedback in the wireless body area network communication system. Compensate for path loss.

In a wireless body area network communication system provided by an embodiment of the present invention, a load resistance and a numerically controlled inductance array are connected in series between the signal electrode and the ground electrode at the receiving end, and a compensation inductance value calculator is connected in parallel with the load resistance and the numerically controlled inductance array, so that the The load resistor can generate a voltage signal according to the excitation signal emitted by the AC signal source at the transmitting end and transmit it to the compensation inductance value calculator, which further enables the compensation inductance value calculator to calculate the compensation inductance value according to the voltage signal and transmit it to the numerical control inductance array, further enabling the numerical control The inductance array determines the compensation inductance from the plurality of inductances included in itself, and then compensates the reverse path loss in the wireless body area network communication system through the compensation inductance. Since the AC signal source at the transmitting end can periodically or aperiodically transmit excitation signals during the change of the human body posture, each time the transmitting end transmits an excitation signal, the receiving end can generate a corresponding voltage signal, and then based on the voltage signal, the The compensation inductance is determined in the numerical control inductance array, so that the reverse path loss in the system can be compensated by the compensation inductance, so that the reverse path loss in the system can be dynamically and effectively compensated during the change of the human body posture, so that the power of the system can be compensated. consumption is greatly reduced.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic structural diagram of a wireless body area network communication system in the prior art;

2 is a schematic structural diagram of a wireless body area network communication system with a compensation function in the prior art;

3 is a schematic structural diagram of a wireless body area network communication system according to an embodiment of the present invention;

4 is a schematic diagram of a specific structure of a wireless body area network communication system according to an embodiment of the present invention;

5 is a schematic diagram of a specific structure of a wireless body area network communication system according to another embodiment of the present invention;

6 is a schematic structural diagram of a compensation inductance value calculator provided by an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a testing system provided by an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

FIG. 3 is a schematic structural diagram of a wireless body area network communication system provided by an embodiment of the present invention. As shown in FIG. 3 , the system includes: a transmitting end 31 and a receiving end 32; wherein, the receiving end 32 includes:

Load resistance 321, digitally controlled inductance array 322 and compensation inductance value calculator 323; wherein,

The load resistor 321 and the digitally controlled inductance array 322 are sequentially connected in series between the signal electrode SE _rx and the ground electrode GE _rx , and the compensation inductance value calculator 323 is connected in parallel with the load resistor 321 and the digitally controlled inductor array 322;

The load resistor 321 is used for generating a voltage signal according to the excitation signal emitted by the transmitting terminal 31;

The compensation inductance value calculator 323 is configured to calculate the compensation inductance value according to the voltage signal;

The digitally controlled inductance array 322 is configured to determine a number of inductances from a plurality of inductances of the digitally controlled inductance array 322 as compensation inductances according to the compensation inductance value, and use the compensation inductance to communicate to the wireless body area network communication system. to compensate for the reverse path loss.

First, the transmitting end 31 is described in detail with reference to FIG. 3 :

The transmitting end 31 includes: a signal electrode SE _tx , an AC signal source 311 and a ground electrode GE _tx which are connected in series in sequence. Among them, the AC signal source 311 periodically or aperiodically generates an excitation signal, which can generate an AC voltage between the signal electrode SE _tx and the ground electrode GE _tx , and the AC voltage is transmitted to the receiving end through the coupling capacitance in the human body and the air 32, so that an AC voltage is generated between the signal electrode SE _rx of the receiving end 32 and the ground electrode GE _rx , and the AC voltage causes the load resistor 321 to generate a voltage signal. Among them, the load resistor is a high-power energy-dissipating resistor that is usually used in products such as large-scale power supply equipment, medical equipment, and power equipment to absorb excess power.

Next, the receiving end 32 is described in detail with reference to FIG. 3 :

The receiving end 32 includes: a signal electrode SE _rx , a load resistor 321 , a digitally controlled inductor array 322 and a ground electrode GE _rx , which are connected in series, and a compensation inductance value calculator 323 connected in parallel with the load resistor 321 and the digitally controlled inductor array 322 .

The first end of the compensation inductance value calculator 323 is electrically connected to the wire between the signal electrode SE _rx and the load resistor 321, and is used to obtain the voltage signal generated by the load resistor 321, so as to calculate the compensation inductance value according to the voltage signal, It should be noted that the compensation inductance value is the optimal inductance value of the inductance for compensating the reverse path loss in the wireless body area network communication system, that is, when the reverse path loss is compensated by the inductance with the compensation inductance value, The compensation effect is optimal; the second end of the compensation inductance value calculator 323 is electrically connected to the numerical control inductance array 322 , so as to send the calculated compensation inductance value to the numerical control inductance array 322 .

It should be noted that the digitally controlled inductance array 322 includes an inductance controller and a plurality of inductances. The inductance controller can determine some or all of the inductances from the plurality of inductances as compensation inductances according to the received compensation inductance values, so as to compensate the compensation inductances. The inductor is connected in series between the ground electrode GE _rx and the load resistor 321 as a whole, so as to compensate the reverse path loss in the wireless body area network communication system.

In the system provided by the embodiment of the present invention, a load resistance and a numerically controlled inductance array are connected in series between the signal electrode and the ground electrode of the receiving end, and a compensation inductance value calculator is connected in parallel with the load resistance and the numerically controlled inductance array, so that the load resistance can be adjusted according to the AC voltage of the transmitting end. The excitation signal emitted by the signal source generates a voltage signal and transmits it to the compensation inductance value calculator, which further enables the compensation inductance value calculator to calculate the compensation inductance value according to the voltage signal and transmit it to the numerical control inductance array, further making the numerical control inductance array from the compensation inductance value from The compensation inductance is determined from the plurality of inductances included in the self, and the reverse path loss in the wireless body area network communication system is compensated by the compensation inductance. Since the AC signal source at the transmitting end can periodically or aperiodically transmit excitation signals during the change of the human body posture, each time the transmitting end transmits an excitation signal, the receiving end can generate a corresponding voltage signal, and then based on the voltage signal, the The compensation inductance is determined in the numerical control inductance array, so that the reverse path loss in the system can be compensated by the compensation inductance, so that the reverse path loss in the system can be dynamically and effectively compensated during the change of the human body posture, so that the power of the system can be compensated. consumption is greatly reduced.

On the basis of the above embodiments, the embodiment of the present invention further describes the numerically controlled inductor array 322 in the above embodiment with reference to FIG. 4 . FIG. 4 is a schematic diagram of a wireless body area network communication system provided by an embodiment of the present invention. A schematic diagram of the specific structure, as shown in FIG. 4 , the numerically controlled inductor array 322 in the system includes:

The first compensation inductance determination module 3221, a plurality of inductances and a plurality of switches; wherein,

Each of the multiple inductors is connected in parallel, the multiple switches are in one-to-one correspondence with the multiple inductors, and each switch is connected in series with the corresponding inductor;

The first compensation inductance determination module 3221 is electrically connected to the plurality of switches, and is configured to determine a number of inductances from the plurality of inductances as compensation inductances according to the compensation inductance values, and generate a plurality of inductances according to the compensation inductances control signals and send to the plurality of switches;

The plurality of switches are used for opening or closing according to the control signal, so as to use the inductance corresponding to the switch in the closed state as a compensation inductance, so that the compensation inductance can be used for the wireless body area network communication system. to compensate for the reverse path loss.

Specifically, as mentioned in the above embodiments, the digitally controlled inductor array 322 includes one inductor controller and multiple inductors. In the embodiment of the present invention, the inductance controller is preferably a first compensation inductance determination module 3221 and a plurality of switches, that is, the inductance controller includes a first compensation inductance determination module 3221 and a plurality of switches. It should be noted that each of the inductances in the plurality of inductances is in a parallel relationship, the plurality of switches and the plurality of inductances are in one-to-one correspondence, and each switch is connected in series with the corresponding inductance.

The first compensation inductance determination module 3221 is electrically connected to a plurality of switches, and is used for determining a part of the inductance or the whole inductance from the plurality of inductances as compensation inductance according to the received compensation inductance value, and generating a control signal based on the determined compensation inductance and sent to multiple switches. The multiple switches can be opened or closed according to the received control signal, so that the inductance corresponding to the switch in the closed state can be used as the compensation inductance, so that the reverse path loss in the wireless body area network communication system can be directly affected by the compensation inductance. to compensate.

In order to explain the embodiments of the present invention more clearly, a plurality of inductors are described:

The inductance values of a plurality of parallel inductors increase sequentially, and the inductance values of adjacent inductors have a relationship of 2 times or approximately 2 times.

It can be understood that, for the system in Figure 4, if the number of inductors is N, the number of switches is also N; if N is 5, the number of inductors is 5, the number of switches is also 5, and , the inductance values of these five inductors increase sequentially from top to bottom. If the five inductances are called inductance 1, inductance 2, inductance 3, inductance 4 and inductance 5 in order from top to bottom, then the inductance value of inductance 2 is twice or approximately the inductance value of inductance 1. 2 times, the inductance value of the inductance 3 is twice or approximately twice the inductance value of the inductance 2, and so on, and will not be repeated here.

Describe the first compensation inductance determination module:

In order to better explain the function of the first compensation inductance determination module, first, the following definition is made: for the multiple inductors in the digitally controlled inductor array 322, any one or more of the multiple inductors connected in parallel to form a combination is called an inductor Subset, it can be understood that there are multiple inductance subsets for these multiple inductors. For example, for inductance 1, inductance 2, inductance 3, inductance 4 and inductance 5 in the above example, inductance 1 can be referred to as an inductance subset, and the combination formed by inductance 1 and inductance 2 in parallel can be referred to as an inductance subset, The combination formed by the inductance 1 , the inductance 2 , the inductance 3 , the inductance 4 , and the inductance 5 in parallel may also be referred to as an inductance subset, and the enumeration of the inductance subsets in this embodiment of the present invention will not be repeated.

The first compensation inductance determination module has pre-stored the total inductance value of each inductance subset, after receiving the compensation inductance value, it compares the total inductance value of each inductance subset with the compensation inductance value, and The inductance in the inductance subset whose magnitude is closest to the compensation inductance value is determined as the compensation inductance.

After the compensation inductance is determined by the first compensation inductance determination module, a control signal is generated and sent to a plurality of switches. For example, for the above example, the control signal is a 5-bit binary digital signal, such as 10001, 00111, etc., wherein 1 controls the switch to be closed, and 0 controls the switch to open. If the compensation inductances determined by the first compensation inductance determination module are inductance 1 and inductance 5, the generated control signal is 10001, wherein the highest bit 1 and the lowest bit 1 are respectively used to control the switch corresponding to inductance 1 and the switch corresponding to inductance 5 , the three 0s in the middle from left to right are used to control the switch corresponding to inductance 2, the switch corresponding to inductance 3, and the switch corresponding to inductance 4, respectively. At this time, the switch corresponding to inductance 1 and the switch corresponding to inductance 5 are closed, and the switch corresponding to inductance 2, the switch corresponding to inductance 3, and the switch corresponding to inductance 4 are all disconnected. The combination is connected in series between the ground electrode GE _rx and the load resistance as a compensation inductance to compensate for the reverse path loss in the wireless body area network communication system.

On the basis of the above embodiments, the embodiment of the present invention further describes the numerically controlled inductor array in the above embodiment with reference to FIG. 5 . FIG. 5 is a schematic diagram of a wireless body area network communication system provided by another embodiment of the present invention. A schematic diagram of the specific structure, as shown in FIG. 5 , the numerical control inductor array 322 in the system includes:

A second compensation inductance determination module 3222, a plurality of inductances, and a plurality of switches; wherein,

Each of the multiple inductors is connected in series, the multiple switches are in one-to-one correspondence with the multiple inductors, and each switch is connected in parallel with the corresponding inductor;

The second compensation inductance determination module 3222 is electrically connected to the plurality of switches, and is configured to determine a number of inductances from the plurality of inductances as compensation inductances according to the compensation inductance values, and generate a plurality of inductances according to the compensation inductances control signals and send to the plurality of switches;

The plurality of switches are used for opening or closing according to the control signal, so as to use the inductance corresponding to the switch in the open state as a compensation inductance, so as to use the compensation inductance to control the wireless body area network communication system. to compensate for the reverse path loss in .

It should be noted that the numerically controlled inductor array 322 in the embodiment of the present invention is a modification of the numerically controlled inductor array 322 in the above-mentioned embodiment. The functions of the components included in the numerically controlled inductor array 322 in this embodiment are similar to those of the components included in the numerically controlled inductor array 322 in the above-mentioned embodiments, and will not be repeated here.

On the basis of the foregoing embodiments, the embodiment of the present invention specifically describes the compensation inductance value calculator in the foregoing embodiments, that is, the compensation inductance value calculator includes:

a reverse path loss value calculation module, configured to calculate the reverse path loss value in the wireless body area network communication system according to the voltage signal;

a reverse path distance calculation module, configured to calculate the reverse path distance in the wireless body area network communication system according to the reverse path loss value;

a reverse coupling capacitance value calculation module, configured to calculate the reverse coupling capacitance value in the wireless body area network communication system according to the reverse path distance;

The compensation inductance value calculation module is used for calculating the compensation inductance value according to the reverse coupling capacitance value.

Specifically, the compensation inductance value calculator provided by the embodiment of the present invention is described in detail with reference to FIG. 6 . FIG. 6 is a schematic structural diagram of the compensation inductance value calculator provided by the embodiment of the present invention. As shown in FIG. 6 , the compensation inductance value The calculator includes: a reverse path loss value calculation module 3231 , a reverse path distance calculation module 3232 , a reverse coupling capacitance value calculation module 3233 and a compensation inductance value calculation module 3234 that are electrically connected in sequence.

Among them, the input end of the reverse path loss value calculation module 3231 is electrically connected to the wire between the load resistance and the signal electrode SE _rx , used to obtain the voltage signal generated by the load resistance, and according to the obtained voltage signal, calculate the wireless body The reverse path loss value in the area network communication system and output.

The input end of the reverse path distance calculation module 3232 is electrically connected to the output end of the reverse path loss value calculation module 3231 for obtaining the reverse path loss value, and according to the obtained reverse path loss value, the wireless body domain is obtained by calculation The reverse path distance in the network communication system and output.

The input end of the reverse coupling capacitance value calculation module 3233 is electrically connected to the output end of the reverse path distance calculation module 3232 for obtaining the reverse path distance, and according to the obtained reverse path distance, the wireless body area network communication is obtained by calculation The value of the reverse coupling capacitor in the system and output.

The input end of the compensation inductance value calculation module 3234 is electrically connected to the output end of the reverse coupling capacitance value calculation module 3233 for obtaining the reverse coupling capacitance value, and calculating the compensation inductance value according to the obtained reverse coupling capacitance value.

On the basis of the foregoing embodiments, the embodiment of the present invention specifically describes the reverse path loss value calculation module in the foregoing embodiments, that is, the reverse path loss value calculation module is further used for:

According to the strength of the excitation signal and the strength of the voltage signal, the total path loss value in the wireless body area network communication system is calculated, and according to the total path loss value and the wireless body area network communication system The forward path loss value is calculated to obtain the reverse path loss value.

Specifically, the total path loss in the wireless body area network communication system includes forward path loss and reverse path loss. In order to calculate the reverse path loss value, it is necessary to know the total path loss value and the forward path loss in the wireless body area network communication system. to the path loss value.

Among them, the method for calculating the total path loss value is: obtain the intensity of the excitation signal emitted by the AC signal source at the transmitting end, and obtain the intensity of the voltage signal generated by the load resistance at the receiving end, and subtract the intensity of the excitation signal and the intensity of the voltage signal, The total path loss value in the wireless body area network communication system can be obtained.

With reference to Fig. 4, the method of obtaining the forward path loss value is described: short-circuit the ground electrode GE _tx at the transmitting end and the ground electrode GE _rx at the receiving end. After the short circuit, turn off each switch in order from top to bottom or from left to right. , each time a switch is closed, the difference between the intensity of the excitation signal and the intensity of the voltage signal is calculated, and the minimum value of all the differences is taken as the forward path loss value.

For example, for inductor 1, inductor 2, inductor 3, inductor 4, and inductor 5, first, short-circuit the ground electrode GE _tx at the transmitting end and the ground electrode GE _rx at the receiving end. After the short circuit, close the switch corresponding to inductor 1, and calculate an excitation signal. The difference between the intensity of the voltage signal and the intensity of the voltage signal; then, close the switch corresponding to the inductance 2, calculate the difference between the intensity of the excitation signal and the intensity of the voltage signal, and so on, you can get 5 difference values, the 5 difference values The minimum value in is taken as the forward path loss value.

It should be noted that, usually, the forward path loss value is calculated before the system is put into use.

On the basis of the foregoing embodiments, the embodiment of the present invention specifically describes the reverse path distance calculation module in the foregoing embodiments, that is, the reverse path distance calculation module is further used for:

According to the reverse path loss value, the reverse path distance in the wireless body area network communication system is calculated by the following formula:

Wherein, D _TR is the reverse path distance, P _bl is the reverse path loss value, and f is the frequency of the excitation signal.

The embodiment of the present invention describes the origin of the above formula:

Since the reverse path loss P _bl only depends on the change of the reverse path distance D _TR , the relationship between the reverse path distance D _TR and the reverse path loss value P _bl can be established through specific tests.

The test steps are as follows:

First, a test system is established. The system is shown in FIG. 7 , wherein FIG. 7 is a schematic structural diagram of a test system provided by an embodiment of the present invention. As shown in FIG. 7 , the test system includes:

The signal electrode SE _tx , the signal electrode SE _rx , the ground electrode GE _tx , the ground electrode GE _rx , the first balun 71 , the second balun 72 , and the vector network analyzer 73 .

The first end of the first balun 71 is electrically connected to the wire between the signal electrode SE _tx and the ground electrode GE _tx , and the second end of the first balun 71 is electrically connected to the vector network analyzer 73 .

The first end of the second balun 72 is electrically connected to the wire between the signal electrode SE _rx and the ground electrode GE _rx , and the second end of the second balun 72 is electrically connected to the vector network analyzer 73 .

The first balun 71 is used to isolate the ground electrode GE _tx from the ground of the vector network analyzer 73 , and the second balun 72 is used to isolate the ground electrode GE _rx from the ground of the vector network analyzer 73 . In order to reduce the coupling effect between cables, both the first balun 71 and the second balun 72 are directly connected to the test instrument.

Then, start the formal test:

Attach the signal electrode SE _tx and the signal electrode SE _rx to the surface of the human body;

The ground electrode GE _tx and the ground electrode GE _rx are directly connected, and the forward path loss value is obtained by short-circuiting the reverse path.

Change the distance between the ground electrode GE _tx and the ground electrode GE _rx , and test the total path loss value under different reverse path distances D _TR . The corresponding reverse path distance D can be obtained by subtracting the forward path loss value from the total path loss value. Reverse path loss value at _TR .

According to a large number of test results, the variation law of the reverse path loss P _bl with the reverse path distance D _TR can be obtained, and based on the least squares method, the reverse path loss value P bl and the reverse path distance D TR and the reverse path loss value P _bl and the reverse path distance D _TR and The relationship between:

On the basis of the foregoing embodiments, the embodiment of the present invention specifically describes the reverse coupling capacitance value calculation module in the foregoing embodiments, that is, the reverse coupling capacitance value calculation module is further used for:

According to the reverse path distance, the reverse coupling capacitance value in the wireless body area network communication system is calculated by the following formula:

Among them, C _air is the reverse coupling capacitance value, D _TR is the reverse path distance, S is the area of the ground electrode, l is the perimeter of the ground electrode, K is the correction factor, ε ₀ is the dielectric constant in vacuum, ε _r is the relative permittivity of human tissue.

Specifically, the usual calculation formula of parallel plate capacitance is not applicable to the calculation of reverse coupling capacitance. This is because the calculation formula of the parallel plate capacitance is only applicable when the distance between the parallel plates is much smaller than the size of the parallel plates. At this time, the charge density on the plates can be considered to be uniform, and the fringe field can be ignored. However, in the wireless body area network communication system, the distance between the two ground electrodes is usually larger than the size of the electrodes. At this time, the fringe field cannot be ignored, and the existence of the human body will also affect the reverse coupling capacitance.

Based on this, a reverse coupling capacitor simulation platform is established by using electromagnetic simulation software. The specific steps are: first, a human body model is established in the electromagnetic simulation software, and the human body is divided into four parts: arms, legs, chest cavity and abdomen. Each section contains multiple organizational layers. After building the human body model, the permittivity and conductivity were imported into each tissue layer. Measure the thickness of tissue layers in different human bodies and import their measurements into the model. In the simulation software, two copper sheets are established as ground electrodes, placed 0.5cm above the human body model, and the distance between the two copper sheets is the reverse path distance D _TR .

Change the distance between the two copper sheets and simulate the reverse coupling capacitance value corresponding to the reverse path distance D _TR , and a series of results can be obtained. At the same time, it is also possible to study the influence of the reverse coupling capacitance value with the different shapes and sizes of the ground electrodes. Based on these simulation results, the relationship between the reverse path distance D _TR and the reverse coupling capacitance value C _air can be calculated:

Among them, C _air is the reverse coupling capacitance value, D _TR is the reverse path distance, S is the area of the ground electrode, l is the perimeter of the ground electrode, K is the correction factor, ε ₀ is the dielectric constant in vacuum, ε _r is the relative permittivity of human tissue. When the ground shapes are circle, triangle, square and hexagon, the parameter K is 0.89, 0.95, 1 and 1.03, respectively.

On the basis of the above embodiments, the embodiments of the present invention specifically describe the compensation inductance value calculation module in the above embodiments, that is, the compensation inductance value calculation module is further used for:

According to the reverse coupling capacitance value, the compensation inductance value is calculated by the following formula:

Among them, L is the compensation inductance value, C _air is the reverse coupling capacitance value, C _{gd, TX} is the capacitance of the ground electrode of the transmitting end to the ground, C _{gd, RX} is the capacitance of the ground electrode of the receiving end to the ground, and f is the excitation the frequency of the signal. Typically, C _gd,TX and C _gd,RX are both 2pF.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. A wireless body area network communication system, comprising: a transmitting end and a receiving end; wherein, the receiving end includes:

the device comprises a load resistor, a numerical control inductor array and a compensation inductance value calculator; wherein,

the load resistor and the numerical control inductance array are sequentially connected in series between a signal electrode and a ground electrode, and the compensation inductance value calculator is connected with the load resistor and the numerical control inductance array in parallel;

the load resistor is used for generating a voltage signal according to the excitation signal transmitted by the transmitting end;

the compensation inductance value calculator is used for calculating to obtain a compensation inductance value according to the voltage signal;

the digital control inductor array is used for determining a plurality of inductors from a plurality of inductors of the digital control inductor array as compensation inductors according to the compensation inductance values, and compensating the reverse path loss in the wireless body area network communication system through the compensation inductors;

the compensation inductance value calculator includes:

the reverse path loss value calculating module is used for calculating to obtain a reverse path loss value in the wireless body area network communication system according to the voltage signal;

a reverse path distance calculation module, configured to calculate a reverse path distance in the wireless body area network communication system according to the reverse path loss value;

a reverse coupling capacitance value calculating module, configured to calculate a reverse coupling capacitance value in the wireless body area network communication system according to the reverse path distance;

and the compensation inductance value calculation module is used for calculating the compensation inductance value according to the reverse coupling capacitance value.

2. The system of claim 1, wherein the digitally controlled inductor array comprises:

the device comprises a first compensation inductance determining module, a plurality of inductors and a plurality of switches; wherein,

each inductor in the plurality of inductors is connected in parallel, the plurality of switches correspond to the plurality of inductors one by one, and each switch is connected with the corresponding inductor in series;

the first compensation inductance determining module is electrically connected with the plurality of switches and used for determining a plurality of inductances from the plurality of inductances according to the compensation inductance values to serve as compensation inductances, generating control signals according to the compensation inductances and sending the control signals to the plurality of switches;

the switches are used for being opened or closed according to the control signal, so that the inductance corresponding to the switch in the closed state is used as compensation inductance, and reverse path loss in the wireless body area network communication system is compensated through the compensation inductance.

3. The system of claim 1, wherein the digitally controlled inductor array comprises:

a second compensation inductance determination module, a plurality of inductances, and a plurality of switches; wherein,

each inductor in the plurality of inductors is connected in series, the plurality of switches correspond to the plurality of inductors one to one, and each switch is connected with the corresponding inductor in parallel;

the second compensation inductance determining module is electrically connected with the plurality of switches and used for determining a plurality of inductances from the plurality of inductances according to the compensation inductance values to serve as compensation inductances, generating control signals according to the compensation inductances and sending the control signals to the plurality of switches;

the switches are used for being opened or closed according to the control signal, so that the inductance corresponding to the switch in the open state is used as compensation inductance, and reverse path loss in the wireless body area network communication system is compensated through the compensation inductance.

4. The system of claim 1, wherein the reverse path loss value calculation module is further configured to:

and calculating to obtain a total path loss value in the wireless body area network communication system according to the intensity of the excitation signal and the intensity of the voltage signal, and calculating to obtain the reverse path loss value according to the total path loss value and a forward path loss value in the wireless body area network communication system.

5. The system of claim 1, wherein the reverse path distance calculation module is further configured to:

and calculating the reverse path distance in the wireless body area network communication system according to the reverse path loss value and by the following formula:

wherein D is_TRFor reverse path distance, P_blFor reverse path loss values, f is the frequency of the excitation signal.

6. The system of claim 1, wherein the reverse coupling capacitance value calculation module is further configured to:

and calculating a reverse coupling capacitance value in the wireless body area network communication system according to the reverse path distance and by the following formula:

wherein, C_airFor reverse coupling of capacitance values, D_TRFor reverse path distance, S is the area of the ground electrode, l is the perimeter of the ground electrode, K is a correction factor, ε₀Is a dielectric constant in vacuum,. epsilon_rIs the relative permittivity of human tissue.

7. The system of claim 1, wherein the compensation inductance value calculation module is further configured to:

and calculating the compensation inductance value according to the reverse coupling capacitance value and by the following formula:

wherein L is the compensation inductance value, C_airFor reverse coupling of capacitance values, C_gd,TXCapacitance of ground electrode to ground, C, of the transmitting end_gd,RXF is the capacitance of the ground electrode of the receiving end to ground, and f is the frequency of the excitation signal.

Images