CN104822158B - The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network - Google Patents

The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network Download PDF

Info

Publication number
CN104822158B
CN104822158B CN201510259528.5A CN201510259528A CN104822158B CN 104822158 B CN104822158 B CN 104822158B CN 201510259528 A CN201510259528 A CN 201510259528A CN 104822158 B CN104822158 B CN 104822158B
Authority
CN
China
Prior art keywords
base stations
lambda
distance
radio frequency
epsilon
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN201510259528.5A
Other languages
Chinese (zh)
Other versions
CN104822158A (en
Inventor
张健
余纯武
董岩松
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University WHU
Original Assignee
Wuhan University WHU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University WHU filed Critical Wuhan University WHU
Priority to CN201510259528.5A priority Critical patent/CN104822158B/en
Publication of CN104822158A publication Critical patent/CN104822158A/en
Application granted granted Critical
Publication of CN104822158B publication Critical patent/CN104822158B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention discloses the method for optimizing position of base station in a kind of radio frequency charging wireless sensor network, the rf wave that the present invention combines the transmitting of two RF base stations produces interference this feature at same sensor node, pass through the overlay analysis to two row electric waves at same wait charge sensors node, relation of the alternate position spike of two RF base stations with waiting charge sensors node charge efficiency is drawn, and then calculates two optimal base station locations of whole network charging effect of sening as an envoy to.This invention is applied in radio frequency charging wireless sensor network, and the charge efficiency for waiting charge node can be significantly increased, so as to extend the life-span of whole wireless sensor network, while reduce the downtime of whole system.

Description

Position optimization method for base station in radio frequency charging wireless sensor network
Technical Field
The invention belongs to the technical fields of wireless sensor networks, radio frequency charging technologies, radio frequency interference and the like, relates to a position optimization method of base stations in a radio frequency charging wireless sensor network, and particularly relates to a base station parking position method for optimizing the charging effect of the whole network in the radio frequency charging wireless sensor network with two base stations.
Background
The wireless sensor network mainly comprises sensor nodes, and the sensor nodes have the functions of signal sensing, calculation storage, wireless communication and the like. The sensor nodes are deployed in the areas to be monitored, and the deployment is usually accomplished by means of aircraft dissemination, manual embedment and the like. The nodes form a network in a self-organizing form and transmit monitored data to a management center in a multi-hop routing mode. The user can browse, inquire and search the relevant monitoring data by accessing the server of the management center.
The wireless sensor network has wide application, and mainly comprises a plurality of fields such as environment detection, industrial and infrastructure monitoring, intelligent home, medical system, military and the like. In addition, a large number of nodes in the wireless sensor network are likely to be randomly scattered or placed in places difficult for people to reach in severe environments or embedded in building structures, battery replacement difficulty is high due to manpower, cost is high, and limited energy becomes an important factor for restricting the development of the type of network. How to supplement power for the sensor nodes more effectively becomes one of the important research directions of the wireless sensor network.
Radio frequency charging technology is an emerging technology for replenishing sensor nodes with electric energy, in which a base station replenishes the sensor nodes that send out charging requests with electric energy by emitting radio frequency electric waves.
Currently, the major teams engaged in the research of the hardware of the radio frequency technology-based wireless chargeable sensor network are the Intel laboratory and the PowerCast company. A radio frequency Identification tag (Wireless Identification Sensing Platform WISP) has been developed jointly by Intel laboratories and washington university, and has Sensing capability, and does not use a battery, and works by using direct current converted from radio frequency energy transmitted by a receiving reader as electric energy. And the wireless chargeable sensor suite developed by PowerCast corporation comprises a radio frequency energy transmitting part, an energy receiving part, a microprocessor part, a sensor part and a radio frequency communication part. The energy transmitting part consists of a radio frequency generating circuit and an antenna and continuously transmits electromagnetic waves with 915MHz central frequency, the energy receiving part receives the electromagnetic waves through the antenna and converts the electromagnetic waves into high-frequency voltage pulses, the voltage is amplified through a voltage doubling rectifying circuit, and the electromagnetic waves are converted into usable electric energy to supply power to the sensor node.
However, the problem of how to optimize the charging effect of the whole network in a wireless sensor network with two base stations still cannot be solved well.
Meanwhile, due to different distances between different base stations and the node of the waiting charging sensor, the radio frequency electromagnetic wave interference phenomenon is generated at the node of the waiting charging sensor by the radio frequency electric waves sent by different base stations due to the phase difference generated by the distance difference, so that the charging efficiency of the node to be charged is influenced. How to well utilize the radio frequency interference phenomenon to improve the charging efficiency of the whole network is the key point of the research of the invention.
Disclosure of Invention
Aiming at the technical problems, the invention provides a method for searching the base station parking position which enables the charging effect of the sensor node of the whole network to be optimal in a radio frequency charging wireless sensor network with two base stations.
The technical scheme adopted by the invention is as follows: a method for optimizing the position of a base station in a radio frequency charging wireless sensor network is characterized by comprising the following steps:
step 1: setting two base stations as ET1 and ET2, setting a node of a waiting charging sensor as S1, setting the distance from ET1 to S1 as r1, the distance from ET2 to S1 as r2, and the wavelength of radio frequency electric waves as lambda, analyzing that when the two base stations simultaneously transmit radio frequency energy in a radio frequency charging wireless sensor network, a radio frequency constructive enhancement phenomenon or a radio frequency destructive attenuation phenomenon exists at the S1;
and 2, step: analyzing the charging efficiency eta of S1 and the phase difference of electromagnetic waves emitted by two base stations at the S1 pointThe relationship of (a);
and 3, step 3: analyzing the optimal parking position of a base station in a radio frequency charging wireless sensor network under the following conditions;
the first condition is as follows: if two base stations ET1, ET2 charge one sensor node S1, then:
only two base stations are controlled to stop on a concentric circle with the distance S1 being k lambda; wherein, lambda is the wavelength of radio frequency electromagnetic wave, k is an integer, k is more than or equal to 1 and less than or equal to 65; because the distance difference between the two base stations on the concentric circles and the S1 node is just an integral multiple of the wavelength, two columns of electromagnetic waves respectively emitted by the two base stations generate constructive interference at the point, so that the energy received at the point is enhanced;
case two: if two base stations ET1, ET2 charge two sensor nodes S1, S2, then:
only two base stations are controlled to stop at the intersection point of the concentric circles with the distance S1 being k lambda and the distance S2 being k lambda; because the distance difference between the two base stations on the intersection point and the S1 node or the S2 node is integral multiple of the wavelength, two columns of electromagnetic waves respectively emitted by the two base stations generate constructive interference at the two points, so that the received energy is enhanced;
case three: if two base stations ET1, ET2 charge three sensor nodes S1, S2, S3, then:
(1) If the S1, the S2 and the S3 are collinear, all sensor nodes can generate constructive interference and the charging effect is optimal only by ensuring that the ET1 and the ET2 are positioned at the same side of the three nodes and the distance difference between the two base stations is k lambda;
(2) If S1, S2 and S3 are not collinear, the coordinates of S2 and S3 are (0,d) and (0-d), respectively, and the coordinate of the S1 node is (x 1, y 1); establishing a plane rectangular coordinate system by taking a connecting line of S2 and S3 as a Y axis and taking a perpendicular bisector of the connecting line as an X axis, and searching two symmetrical points A (-c, 0) and B (c, 0) on the X axis to ensure that the difference between the distance from A to S1 and the distance from B to S1 is k lambda, if the two points exist, two base stations respectively stop at the two points, and the simultaneous constructive interference at the positions of S1, S2 and S3 can be realized; since ET1 and ET2 are equidistant from S2 at this time, enhancement is provided for S2; ET1 is equidistant from ET2 to S3, so the enhancement is for S3; the distance between ET1 and S1 minus the distance between ET2 and S1 is k lambda, so that the distance is enhanced for S1;
case four: if two base stations ET1, ET2 charge N sensor nodes, and N > 3, then:
(1) If the N sensor nodes are collinear, all the sensor nodes can generate constructive interference and the charging effect is optimal only by ensuring that ET1 and ET2 are positioned at the same side of the N nodes and the distance difference between two base stations is k lambda;
(2) If the N sensor nodes are not collinear, firstly deducing a node charging efficiency eta formula, wherein each eta value corresponds to a value epsilon, and further corresponds to a distance interval [ k lambda-epsilon, k lambda + epsilon](ii) a If the distance difference between the two base stations and the waiting charging sensor node falls into the interval, the charging efficiency of the node is at least eta; optionally selecting three nodes from the N nodes, constructing a plane rectangular coordinate system and calculating the stop positions of the two mobile base stations ET1 and ET2 according to the method in the third case, and sharingThe method comprises the steps that (1) selection is carried out, at the moment, constructive interference can be achieved at three selected sensor nodes, the received energy is obviously enhanced, and for each selection, the distance difference between the two base station parking positions and the sensor nodes waiting to be charged is k lambda, k is a variable, and the maximum value of k is m; thus N node charging problems are commonA seed scheme is adopted; optionally, two schemes are set as A and B, and for the remaining N-3 nodes, the distance difference between the node and two base stations is respectively calculated, and the following judgment is carried out:
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A is greater than the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, the scheme A is excellent;
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A = the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, comparing the absolute values of the distance differences between the nodes falling into the interval [ k lambda-epsilon, k lambda + epsilon ] and the two base stations in the two schemes with the sum of the sum and the sum of the sum;
after all schemes are considered, an optimal solution is obtained.
Preferably, the radio frequency interference phenomenon described in step 1 includes the following cases:
when r1= r2= λ, the distance difference between the two base stations and S1 is 0, and if the two base stations are synchronized, the phase difference generated thereby is 0, and the two base stations generate a radio frequency constructive enhancement phenomenon at S1;
when r1= r2= λ/2, the distance difference between the two base stations to S1 is λ/2, and if the two base stations are synchronized, the resulting phase difference is pi, and the two base stations generate the radio frequency destructive attenuation phenomenon at S1.
Preferably, the specific implementation process of step 2 is as follows: the phase difference of two lines of waves emitted by two base stations ET1 and ET2 at the S1 point is [ -pi, pi]Δ r is the absolute value of the difference between the two distances, i.e.: Δ r = | r 1 -r 2 L. the method is used for the preparation of the medicament. Taking ε as the absolute value of the distance difference to take the wavelength remainder, i.e.: ε = Δ r% λ (λ is the radio frequency electromagnetic wave wavelength), if ε&gt, [ lambda ]/2, [ epsilon ] = [ lambda ] - [ epsilon ]. Since there is a linear relationship between the phase difference and the distance difference,the phase difference at ε, therefore:
let the equations of vibration of the radio frequency electromagnetic waves emitted by ET1 and ET2 be:
y1＝A1cos(wt)；
y2＝A2cos(wt)；
the sum amplitude of the two trains of waves at point S1 is a:
wherein A1 is the amplitude of electromagnetic waves emitted by ET1, A2 is the amplitude of electromagnetic waves emitted by ET2, w is the vibration frequency, and t is time;
since the intensity of a wave is proportional to the square of the wave amplitude, andthe intensity of the two superposed waves is:
wherein I is the intensity after superposition, I1 is the intensity when the amplitude is A1, and I2 is the intensity when the amplitude is A2; when I1= I2:
when in useWhen I =4I1, constructive interference occurs at the S1 point;
when in useIf not 0, assuming the charging efficiency η at S1, then:
byIt is known that:and further obtaining the relation between the charging efficiency eta and the absolute value of the distance difference between the two base stations and S1 to the wavelength residue epsilon:
when η =0.95, ε =0.0718 λ;
when η =0.90, ε =0.1025 λ;
when η =0.85, ε =0.1267 λ;
when η =0.80, ε =0.1477 λ.
Preferably, the two base stations ET1 and ET2 in step 3 charge the three non-collinear sensor nodes S1, S2 and S3, find two symmetrical points a (-c, 0) and B (c, 0) on the X-axis, and the two mobile base stations respectively stop at the two points, so that the distance between ET1 and S1 is k λ different from the distance between ET2 and S1; the specific calculation process is as follows:
obtained by the formula (2):
(1) and (3) obtaining:
to solve the above equation, 4x needs to be satisfied 1 2 –k 2 λ 2 >0；
If 4x 1 2 –k 2 λ 2 &And (l) =0, i.e., (- | k λ |/2)<x 1 &The angle is less than the angle S2S1S3, and the angle S1S2S3 is less than the angle K lambda |/2Small acute angle, and angle S1S3S2 is a small acute angle; the optimal docking position of the base station in this case is as follows:
and (3) setting the projection of the point S1 on the Y axis as a point T, distributing ET1 and ET2 on two sides of the point T, and setting the distances between the ET1 and the point T and between the ET2 and the point T to be k lambda/2.
According to the invention, by combining the characteristic that radio frequency electric waves emitted by two radio frequency base stations generate interference phenomena at the same sensor node, the relationship between the position difference of the two radio frequency base stations and the charging efficiency of the sensor node to be charged is obtained through the superposition analysis of two rows of electric waves at the same sensor node to be charged, and then the positions of the two base stations which enable the charging effect of the whole network to be optimal are calculated. The invention is applied to the radio frequency charging wireless sensor network, and can greatly improve the charging efficiency of the nodes to be charged, thereby prolonging the service life of the whole wireless sensor network and simultaneously reducing the downtime of the whole system.
Drawings
FIG. 1: is a schematic diagram of a wireless sensor network structure with a base station in the embodiment of the invention;
FIG. 2: the schematic diagram of the charging situation of two base stations to one node in the embodiment of the invention;
FIG. 3: is a schematic diagram of the collinear situation of three sensor nodes in the embodiment of the invention;
FIG. 4: in the embodiment of the invention, three sensor nodes are not collinear and are 4x 1 2 –k 2 λ 2 &gt, 0 case diagram;
FIG. 5: in the embodiment of the invention, three sensor nodes are not collinear and are 4x 1 2 –k 2 λ 2 &And the =0 situation is shown schematically.
Detailed Description
In order to facilitate the understanding and implementation of the present invention for those of ordinary skill in the art, the present invention is further described in detail with reference to the accompanying drawings and examples, it is to be understood that the embodiments described herein are merely illustrative and explanatory of the present invention and are not restrictive thereof.
The invention provides a method for optimizing the position of a base station in a radio frequency charging wireless sensor network, which comprises the following steps:
step 1: setting two base stations as ET1 and ET2, setting a node of a sensor waiting to be charged as S1, setting the distance from ET1 to S1 as r1, the distance from ET2 to S1 as r2, and the wavelength of radio frequency electric waves as lambda, and analyzing the radio frequency interference phenomenon existing at the S1 when the two base stations simultaneously transmit radio frequency energy in the radio frequency charging wireless sensor network;
as shown in fig. 1, the distances from ET1, ET2 to S1 are λ, which is exactly the length of one wavelength, and at this time, since the distance difference from two base stations to S1 is 0, the resulting phase difference is 0 (the two base stations are synchronized), and the two base stations generate a radio frequency constructive enhancement phenomenon at the sensor node to be charged.
ET1 is a distance λ from S1, exactly one wavelength long; the distance between ET3 and S1 is lambda/2, the length of half wavelength, at this time, because the distance difference between two base stations and S1 is lambda/2, the phase difference generated thereby is pi (the two base stations are synchronous), and the two base stations generate destructive attenuation phenomenon at the nodes of the sensor to be charged.
The invention is based on the consideration of how to better utilize constructive interference and avoid destructive interference so as to optimize the charging efficiency of the whole network.
Step 2: analyzing charging efficiency eta of S1 and phase difference between two base stationsThe relationship of (1);
let the phase difference of two lines of waves emitted by two base stations ET1 and ET2 at the point S1 be [ - π, π]Δ r is the absolute value of the difference between the two distances, i.e.: Δ r = | r 1 -r 2 L. Taking ε as the absolute value of the distance difference and taking the wavelength remainder, i.e.: ε = Δ r% λ (λ is the radio frequency electromagnetic wave wavelength), if ε&gt, [ lambda ]/2, [ epsilon ] = [ lambda ] - [ epsilon ]. Since there is a linear relationship between the phase difference and the distance difference,the phase difference at ε, therefore:
let the vibration equations of the radio frequency electromagnetic waves emitted by ET1 and ET2 be:
y1＝A1cos(wt)；
y2＝A2cos(wt)；
the sum amplitude of the two trains of waves at point S1 is a:
wherein A1 is the amplitude of the electromagnetic wave emitted by ET1, A2 is the amplitude of the electromagnetic wave emitted by ET2, w is the vibration frequency, and t is the time.
Since the intensity of the wave is proportional to the square of the wave amplitudeThe intensity of the two superposed waves is:
wherein I is the intensity after superposition, I1 is the intensity when the amplitude is A1, and I2 is the intensity when the amplitude is A2; when I1= I2:
when in useWhen, I =4I1; constructive interference is generated at the S1 point;
when in useWhen not 0, setAt S1, the charging efficiency η is:
byIt is known that:and further obtaining the relation between the charging efficiency eta and the absolute value of the distance difference between the two base stations and S1 to the wavelength residue epsilon:
when η =0.95, ε =0.0718 λ;
when η =0.90, ε =0.1025 λ;
when η =0.85, ε =0.1267 λ;
when η =0.80, ε =0.1477 λ.
And step 3: analyzing the optimal parking position of a base station in a radio frequency charging wireless sensor network under the following conditions;
the first condition is as follows: if two base stations ET1, ET2 charge one sensor node S1, then:
referring to fig. 2, it is only necessary to control two base stations to stop on a concentric circle with a distance S1 of k λ (λ is the wavelength of the radio frequency electromagnetic wave, and k is an integer). Because the distance difference between two base stations on the concentric circles and the S1 node is just an integral multiple of the wavelength, two columns of electromagnetic waves respectively emitted by the two base stations generate constructive interference at the point, so that the received energy at the point is enhanced.
Case two: if two base stations ET1, ET2 charge two sensor nodes S1, S2, then:
two base stations are controlled to stop at an intersection point on a concentric circle with the distance S1 being k lambda (lambda is the wavelength of radio frequency electromagnetic waves, and k is an integer) and the distance S2 being k lambda. Because the distance difference between two base stations at the intersection point, whether to the S1 node or the S2 node, is an integral multiple of the wavelength, two rows of electromagnetic waves respectively emitted by the two base stations generate constructive interference at the two points, so that the received energy is enhanced.
Case three: if two base stations ET1, ET2 charge three sensor nodes S1, S2, S3, then:
(1) Referring to fig. 3, if S1, S2, and S3 are collinear, it is only necessary to ensure that ET1 and ET2 are located at the same side of the three nodes and the distance difference between the two base stations is k λ, so that constructive interference can be generated at all the three nodes, and the node charging effect is optimal.
(2) Referring to fig. 4, if S1, S2, and S3 are not collinear, let the coordinates of S2 and S3 be (0,d) and (0, -d), respectively, and the coordinate of S1 node be (x 1, y 1); a connecting line of S2 and S3 is used as a Y axis, a plane rectangular coordinate system is established by using a perpendicular bisector of the connecting line as an X axis, two symmetrical points A (-c, 0) and B (c, 0) are searched on the X axis, and the two mobile base stations respectively stop at the two points, so that the difference between the distance from A (ET 1) to S1 and the distance from B (ET 2) to S1 is k lambda. Since ET1 is the same as ET2 to S2, ET1 is the same as ET2 to S3 for S2 enhancement, and ET3 is enhanced for S3; the distance between ET1 and S1 minus the distance between ET2 and S1 is k lambda, so the distance is enhanced for S1;
the specific calculation process of the points A and B is as follows:
obtained by the formula (2):
(1) and (3) obtaining:
to solve the above equation, 4x needs to be satisfied 1 2 –k 2 λ 2 &gt, 0, which is easily satisfied because the wavelength is on the order of decimeters.
Please refer to fig. 5, if 4x 1 2 –k 2 λ 2 < =0, i.e., (- | k λ |/2)<x 1 &And (| k λ |/2), wherein the | < S2S1S3 is a large obtuse angle, the < S1S2S3 is a small acute angle, and the < S1S3S2 is a small acute angle, and the solution of the base station parking position under the condition is as follows:
and (3) setting the projection of the point S1 on the Y axis as a point T, distributing ET1 and ET2 on two sides of the point T, and setting the distances between the point ET1 and the point T and between the point ET2 and the point T to be k lambda/2. At the moment, the distance between ET1 and S1 is equal to the distance between ET2 and S1, constructive interference is generated at the point S1, and energy is enhanced; for S2, the distance between ET2 to S2 differs from the distance between ET1 to S2 by k λ, producing constructive interference; for S3, the distance between ET1 to S3 and the distance between ET2 to S3 differ by k λ, producing constructive interference.
Case four: if two base stations ET1, ET2 charge N sensor nodes, and N > 3, then:
(1) If the N sensor nodes are collinear, all the sensor nodes can be optimally charged only by ensuring that ET1 and ET2 are positioned at the same side of the N nodes and the distance difference between two base stations is k lambda (k is an integer and lambda is the wavelength of radio frequency electromagnetic waves).
(2) If the N sensor nodes are not collinear, firstly deducing a node charging efficiency eta formula, wherein each eta value corresponds to a value epsilon, and further corresponds to a distance interval [ k lambda-epsilon, k lambda + epsilon]. If the distance difference between the two base stations and the waiting charging sensor node falls within the interval, the charging efficiency of the node is at least eta. Optionally selecting three nodes from the N nodes, constructing a plane rectangular coordinate system and calculating the stop positions of the two mobile base stations ET1 and ET2 according to the method in the third case, and sharingAnd in the selection, constructive interference can be realized at the selected three sensor nodes, the receivable energy is obviously enhanced, and the distance difference between the two base station parking positions and the sensor nodes waiting for charging is k lambda, k is a variable, and the maximum value of k is m. Thus N node charging problems are commonAnd (4) carrying out a scheme. Optionally, two schemes are set as A and B, for the remaining N-3 nodes, the distance difference between the node and two base stations is respectively calculated, and the following judgment is carried out:
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A is greater than the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, the scheme A is excellent;
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A = the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, comparing the sum of the absolute values of the distance differences between the nodes falling into the interval [ k lambda-epsilon, k lambda + epsilon ] and the two base stations in the two schemes and the sum of the absolute values of the distance differences between the nodes falling into the interval [ k lambda-epsilon, k lambda + epsilon ] and the two base stations, and determining that the sum is small;
after all schemes are considered, an optimal solution is obtained.
It should be understood that parts of the specification not set forth in detail are well within the prior art.
It should be understood that the above description of the preferred embodiments is given for clarity and not for any purpose of limitation, and that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (4)

1. A method for optimizing the position of a base station in a radio frequency charging wireless sensor network is characterized by comprising the following steps:
step 1: setting two base stations as ET1 and ET2, setting a node of a waiting charging sensor as S1, setting the distance from ET1 to S1 as r1, the distance from ET2 to S1 as r2, and the wavelength of radio frequency electromagnetic waves as lambda, analyzing that when the two base stations simultaneously transmit radio frequency energy in a radio frequency charging wireless sensor network, a radio frequency constructive enhancement phenomenon or a radio frequency destructive attenuation phenomenon exists at the S1;
step 2: analyzing the charging efficiency eta of S1 and the phase difference of electromagnetic waves emitted by two base stations at the S1 pointThe relationship of (a);
and step 3: analyzing the optimal parking position of a base station in a radio frequency charging wireless sensor network under the following conditions;
the first condition is as follows: if two base stations ET1, ET2 charge one sensor node S1, then:
only two base stations are controlled to stop on a concentric circle with the distance S1 being k lambda; wherein, lambda is the wavelength of radio frequency electromagnetic wave, k is an integer, k is more than or equal to 1 and less than or equal to 65;
and a second condition: if two base stations ET1, ET2 charge two sensor nodes S1, S2, then:
only two base stations are controlled to stop at an intersection point on a concentric circle with the distance S1 being k lambda and the distance S2 being k lambda;
and a third situation: if two base stations ET1, ET2 charge three sensor nodes S1, S2, S3, then:
(1) If the S1, the S2 and the S3 are collinear, all the sensor nodes can generate constructive interference and the charging effect is optimal only by ensuring that the ET1 and the ET2 are positioned at the same side of the three nodes and the distance difference between the two base stations is k lambda;
(2) If S1, S2 and S3 are not collinear, the coordinates of S2 and S3 are (0,d) and (0-d), respectively, and the coordinate of the S1 node is (x 1, y 1); establishing a plane rectangular coordinate system by taking a connecting line of S2 and S3 as a Y axis and a perpendicular bisector of the connecting line as an X axis, and searching two symmetrical points A (-c, 0) and B (c, 0) on the X axis to ensure that the difference between the distance from A to S1 and the distance from B to S1 is k lambda, if the two points exist, two base stations respectively stop at the two points, so that the simultaneous constructive interference at the positions of S1, S2 and S3 can be realized;
case four: if two base stations ET1, ET2 charge N sensor nodes, and N > 3, then:
(1) If the N sensor nodes are collinear, all the sensor nodes can generate constructive interference and the charging effect is optimal only by ensuring that ET1 and ET2 are positioned at the same side of the N nodes and the distance difference between two base stations is k lambda;
(2) If the N sensor nodes are not collinear, firstly deducing a node charging efficiency eta formula, wherein each eta value corresponds to a value epsilon, and further corresponds to a distance interval [ k lambda-epsilon, k lambda + epsilon](ii) a If the distance difference between the two base stations and the waiting charging sensor node falls into the interval, the charging efficiency of the node is at least eta; optionally selecting three nodes from the N nodes, constructing a plane rectangular coordinate system and calculating the stopping positions of the two mobile base stations ET1 and ET2 according to the mode in the third case, and sharingThe method comprises the steps that (1) selection is carried out, at the moment, constructive interference can be achieved at three selected sensor nodes, the received energy is obviously enhanced, and for each selection, the distance difference between the two base station parking positions and the sensor nodes waiting to be charged is k lambda, k is a variable, and the maximum value of k is m; thus N node charging problems are commonA seed scheme is adopted; optionally, two of the schemes are set to A, B, and the rest N-3 areAnd the node respectively calculates the distance difference between the node and the two base stations and judges the following steps:
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A is greater than the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, the scheme A is excellent;
if the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme A = the number of nodes with the distance difference falling into [ k lambda-epsilon, k lambda + epsilon ] in the scheme B, comparing the sum of the absolute values of the distance differences between the nodes falling into the interval [ k lambda-epsilon, k lambda + epsilon ] and the two base stations in the two schemes and the sum of the absolute values of the distance differences between the nodes falling into the interval [ k lambda-epsilon, k lambda + epsilon ] and the two base stations, and determining that the sum is small;
after all schemes are considered, an optimal solution is obtained.
2. The method of claim 1, wherein the method comprises the steps of: the radio frequency interference phenomenon described in step 1 includes the following situations:
when r1= r2= λ, the distance difference between the two base stations and S1 is 0, and if the two base stations are synchronized, the phase difference generated thereby is 0, and the two base stations generate a radio frequency constructive enhancement phenomenon at S1;
when r1= r2= λ/2, the distance difference between the two base stations to S1 is λ/2, and if the two base stations are synchronized, the resulting phase difference is pi, and the two base stations generate the radio frequency destructive attenuation phenomenon at S1.
3. The method for optimizing the location of the base station in the radio frequency charging wireless sensor network according to claim 1, wherein the specific implementation process of the step 2 is as follows:
let the phase difference of two lines of waves emitted by two base stations ET1 and ET2 at the point S1 be [ - π, π]Δ r is the absolute value of the difference between the two distances, i.e.: Δ r = | r 1 -r 2 L, |; taking ε as the absolute value of the distance difference and taking the wavelength remainder, i.e.: ε = Δ r% λ (λ is the radio frequency electromagnetic wave wavelength), if ε&gt, [ lambda ]/2, [ epsilon ] = [ lambda ] - [ epsilon ]; since there is a linear relationship between the phase difference and the distance difference,the phase difference at ε, therefore:
let the equations of vibration of the radio frequency electromagnetic waves emitted by ET1 and ET2 be:
y1＝A1cos(wt)；
y2＝A2cos(wt)；
the sum amplitude of the two columns of waves at point S1 is a:
wherein A1 is the amplitude of electromagnetic waves emitted by ET1, A2 is the amplitude of electromagnetic waves emitted by ET2, w is the vibration frequency, and t is time;
since the intensity of the wave is proportional to the square of the wave amplitudeThe intensity of the two superposed waves is:
wherein I is the intensity after superposition, I1 is the intensity when the amplitude is A1, and I2 is the intensity when the amplitude is A2;
when I1= I2:
when in useWhen I =4I1, constructive interference occurs at the S1 point;
when the temperature is higher than the set temperatureIf not 0, assuming the charging efficiency η at S1, then:
byIt is known that:and further obtaining the relation between the charging efficiency eta and the absolute value of the distance difference between the two base stations and S1 to the wavelength residue epsilon:
when η =0.95, ε =0.0718 λ;
when η =0.90, ε =0.1025 λ;
when η =0.85, ε =0.1267 λ;
when η =0.80, ε =0.1477 λ.
4. The method of claim 1, wherein the two base stations ET1 and ET2 in step 3 charge three non-collinear sensor nodes S1, S2 and S3, two symmetrical points a (-c, 0) and B (c, 0) are found on the X-axis, and two mobile base stations respectively stop at the two points, so that the difference between the distance between ET1 and S1 and the distance between ET2 and S1 is k λ; the specific calculation process is as follows:
obtained by the formula (2):
(1) and (3) obtaining:
to solve the above equation, 4x needs to be satisfied 1 2 –k 2 λ 2 >0；
If 4x 1 2 –k 2 λ 2 &And (l) =0, i.e., (- | k λ |/2)<x 1 &The angle is less than the angle S1S2S3, less than the angle S1S 3; the optimal docking position of the base station in this case is as follows:
and (3) setting the projection of the point S1 on the Y axis as a point T, distributing ET1 and ET2 on two sides of the point T, and setting the distances between the ET1 and the point T and between the ET2 and the point T to be k lambda/2.
CN201510259528.5A 2015-05-20 2015-05-20 The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network Expired - Fee Related CN104822158B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201510259528.5A CN104822158B (en) 2015-05-20 2015-05-20 The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201510259528.5A CN104822158B (en) 2015-05-20 2015-05-20 The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network

Publications (2)

Publication Number Publication Date
CN104822158A CN104822158A (en) 2015-08-05
CN104822158B true CN104822158B (en) 2018-03-02

Family

ID=53732296

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201510259528.5A Expired - Fee Related CN104822158B (en) 2015-05-20 2015-05-20 The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network

Country Status (1)

Country Link
CN (1) CN104822158B (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105704731B (en) * 2016-04-28 2018-11-30 杭州电子科技大学 Omnidirectional's charging base station deployment method of wireless chargeable sensing network
CN105722091B (en) * 2016-04-28 2018-11-13 杭州电子科技大学 The orientation charging base station deployment method of wireless chargeable sensing network
CN106851568B (en) * 2017-01-18 2019-10-29 南京邮电大学 It is a kind of optimize wireless sensor network life span base station location determine method
CN108449803B (en) * 2018-04-02 2020-07-31 太原理工大学 Predictable energy management and mission planning method in wireless sensor network
CN108770001B (en) * 2018-04-20 2021-02-12 西安电子科技大学 Wireless chargeable sensor network optimization method based on memetic algorithm
CN110278567B (en) * 2019-05-21 2021-12-07 杭州电子科技大学 K-fence construction and charger optimized deployment method of wireless chargeable sensor network

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103368751A (en) * 2013-07-01 2013-10-23 杭州电子科技大学 Non-contact type charging node deploying method facing to sensor network

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130336185A1 (en) * 2012-06-19 2013-12-19 The Research Foundation For The State University Of New York Apparatus and method for recharge-triggered wake-up for power management in wireless sensor networks

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103368751A (en) * 2013-07-01 2013-10-23 杭州电子科技大学 Non-contact type charging node deploying method facing to sensor network

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Multi-vehicle Coordination for Wireless Energy Replenishment in Sensor Networks;Cong Wang,et.al.;《Parallel & Distributed Processing (IPDPS), 2013 IEEE 27th International Symposium on》;20130524;全文 *
RF Energy Harvesting for WSNs via Dynamic Control of Unmanned Vehicle Charging;Fahira Sangare,et.al.;《Wireless Communications and Networking Conference (WCNC), 2015 IEEE》;20150312;全文 *
无线传感器网络RCF-MAC协议研究;张健，董岩松，刘丹丹;《传感器与微系统》;20150228;第34卷(第2期);全文 *

Also Published As

Publication number Publication date
CN104822158A (en) 2015-08-05

Similar Documents

Publication Publication Date Title
CN104822158B (en) The method for optimizing position of base station in a kind of radio frequency charging wireless sensor network
US11445523B2 (en) Scheduling communications in a wireless network
Nazib et al. Energy-efficient and fast data collection in UAV-aided wireless sensor networks for hilly terrains
Ma et al. Adaptive triangular deployment algorithm for unattended mobile sensor networks
Nazir et al. Classification of localization algorithms for wireless sensor network: A survey
Jamal et al. Low-energy adaptive clustering hierarchy (LEACH) enhancement for military security operations
JP2019506833A (en) Improving wireless energy transfer using electromagnetic alignment
JP2007506963A (en) Network for checking the location of the wireless tag
Lee et al. Gradual cluster head election for high network connectivity in large-scale sensor networks
Yu et al. A fast hierarchical physical topology update scheme for edge-cloud collaborative IoT systems
Vivekanandan et al. Concentric anchor-beacons (CAB) localization for wireless sensor networks
Wu et al. An intelligent target localization in wireless sensor networks
Xu et al. An improved MDS localisation algorithm for a WSN in a sub-surface mine
Vijayan et al. Deterministic Centroid Localization for Improving Energy Efficiency in Wireless Sensor Networks
Shen et al. A RFID based localization algorithm applying trilateration for wireless sensor networks
Vojdani et al. Localization in anchor less wireless sensor network
Sahu et al. Energy-efficient grid-based data dissemination in wireless sensor networks
Abbas et al. Investigation of energy efficient protocols based on stable clustering for enhancing lifetime in heterogeneous WSNs
Farrag et al. Different aspects of localization problem for wireless sensor networks: A review
Zhou et al. Distributed locating algorithm MDS-MAP (LF) based on low-frequency signal
Leuschner The design of a simple energy efficient routing protocol to improve wireless sensor network lifetime
Chen et al. A node division location detection scheme for chain‐type wireless sensor networks
Orman et al. Intelligent node placement using GA (INPGA) protocol in wireless sensor networks
Alhmiedat et al. Tracking multiple mobile targets based on ZigBee standard
Kotwal et al. RSSI WSN localization with Analysis of Energy Consumption and Communication

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
EXSB Decision made by sipo to initiate substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20180302

Termination date: 20190520