CN109495843B - A fixed-point wireless charging base station deployment method based on convex hull selection - Google Patents

Abstract

The invention discloses a method for deploying a fixed-point wireless charging base station based on convex hull selection. The location planning of charging base stations in existing wireless rechargeable sensor networks lacks flexibility, and there are certain deficiencies in practical applications. The present invention is as follows: 1. A plane rectangular coordinate system is established, and n common nodes corresponding to the respective positions of the n wireless rechargeable sensors are placed in the plane rectangular coordinate system. 2. Find the deployment position of the candidate base station, and determine the coverage node set of the candidate base station. 3. Determine the deployment location of the charging base station. 4. Arrange charging base stations on the deployment positions of the base stations determined in steps 2 and 3. The present invention improves the effect of the deployment position of the charging base station by calculating the convex hull of each common node, and greatly reduces the amount of calculation. The present invention gets rid of the constraints in the prior method that the base station needs to be assumed to be in certain fixed areas in advance, and is based on the position information of the wireless rechargeable sensor in the wireless sensor network.

Description

A fixed-point wireless charging base station deployment method based on convex hull selection

technical field

The invention belongs to the technical field of wireless rechargeable sensor networks, and in particular relates to a method for deploying a fixed-point wireless charging base station based on convex hull selection.

Background technique

5G technology has greatly improved in terms of communication speed and power consumption. Therefore, the Internet has also moved from mobile Internet to intelligent Internet, and our life will become very convenient with the advent of the 5G era. Sensor devices are the basis for realizing intelligent interconnection, and wireless charging technology provides a solution to the energy problem of sensor networks, so wireless rechargeable sensors emerge as the times require. In wireless rechargeable sensor networks, the most important issue is how to deploy the fewest charging base stations to meet the energy demand of the entire sensor network. The cost of charging base stations is very high. How to choose the type of charging base stations and reduce redundant base stations can effectively reduce The operating cost of the entire sensor network.

At present, regarding the deployment of charging base stations in wireless rechargeable sensor networks, there have been some studies based on the different characteristics of charging base stations. Hao Peng et al. proposed a wireless charging technology based on beamforming technology in the patent "A Directional Adaptive Wireless Charging Technology Based on Beamforming" (Patent No.: CN103441583A). The charging method can improve the distance of wireless charging, and can improve the efficiency of wireless charging compared with the resonant wireless charging method, but the patent only focuses on the working mode of a single charging base station, and does not involve the optimization of the number of wireless charging base stations in the sensor network. . Wu Yifan et al. proposed a method for location planning of wireless charging base stations in the patent "A Method for Deploying Non-contact Charging Nodes for Sensor Networks" (Patent No.: CN201310276000.X). In this method, the area that needs to be charged is first gridded, all sensor nodes are inside the grid, and then wireless charging base stations are deployed on the grid points. The base stations deployed in this deployment method are not necessarily in the best position In addition, he also assumes that the charging base station has a charging radius, and the value of the charging radius will cause a certain amount of error in the deployment of charging base stations. . Therefore, it is very important to propose a base station deployment method in which the location of the charging base station can be flexibly planned and the number of charging base stations can be optimized by using the wireless charging base station with a long charging distance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a fixed-point wireless charging base station deployment method based on convex hull selection.

The concrete steps of the present invention are as follows:

Step 1. Establish a plane rectangular coordinate system, and place n common nodes corresponding to the respective positions of the n wireless rechargeable sensors into the plane rectangular coordinate system. The set composed of n ordinary nodes is the ordinary node set U. Assign 1 to i.

Step 2: Find the deployment position of the candidate base station, and determine the coverage node set of the candidate base station.

2-1. Establish a candidate base station set S _i that is initially an empty set. A candidate sensor set CU is established. The candidate sensor set CU, let the candidate sensor set CU be equal to the common node set U.

2-2. Calculate the convex hull of the candidate sensor set CU according to the coordinates of each common node in the candidate sensor set CU, and assign 1 to k.

2-3. Select one vertex of the convex hull obtained in step 2-2 as the first covering node qi _,1 of the ith candidate base station c _i , and add it to the covering node set Qi of the _ith candidate base station. Remove the first coverage node q _i,1 of the i-th candidate base station c _i from the candidate sensor set CU. The coordinates of the first coverage node q _i,1 of the i-th candidate base station c _i are ( _xi,1 ,y _i,1 ). The position of the first coverage node qi _,1 of the ith candidate base station c _i is taken as the initial position of the ith candidate base station. The coordinates of the initial position of the i-th candidate base station are (ai _,1 ,bi _,1 ), a _i,1 = _xi,1 , and bi _,1 =y _i,1 .

2-4. Take the common node in the candidate sensor set CU with the closest distance to the coordinates (a _i,k ,b _i,k ) as the candidate node. The coordinates of the candidate nodes are (x', y'). Remove the candidate node from the candidate sensor set CU.

2-5. Calculate the base station update prediction coordinates (a', b'); wherein, the expression of a' is shown in formula (1); the expression of b' is shown in formula (2);

η为充电基站与无线可充电传感器紧挨在一起时的传输效率；α的取值为

G_t为充电基站的发射天线的增益大小；G_r为无线可充电传感器的接收天线的增益大小；λ为充电基站与无线可充电传感器进行无线传输时所用电磁波的波长。In equations (1) and (2), w _i,j represents the power of the wireless rechargeable sensor corresponding to the jth coverage node q _i,j of the ith candidate base station c _i ; x _i,j is the ith candidate The abscissa of the jth covering node qi,j of the base station c _i ; y _i,j is the ordinate of the jth covering node q _{i,j of} the ith candidate base station c _i ; w′ is the corresponding The power of the wireless rechargeable sensor; the value of β is

η is the transmission efficiency when the charging base station and the wireless rechargeable sensor are close together; the value of α is

G _t is the gain of the transmitting antenna of the charging base station; G _r is the gain of the receiving antenna of the wireless rechargeable sensor; λ is the wavelength of the electromagnetic wave used in the wireless transmission between the charging base station and the wireless rechargeable sensor.

如式(3)所示；2-6. Calculate the charging dormancy duration of the ith candidate base station c _i that is recorded as a candidate node

As shown in formula (3);

In formula (3), T is the charging cycle of the charging base station, and its expression is shown in formula (4). t _i,j is the charging duration of the j-th coverage node of the i-th candidate base station c _i , and its expression is shown in equation (5). t' is the charging duration of the candidate node, and its expression is shown in equation (6).

In formula (4), CM is the battery capacity of each wireless rechargeable sensor. w _max is the power of the sensor with the highest power among the wireless rechargeable sensors.

d_ij为第i个候选基站c_i的第j个覆盖节点q_ij与坐标(a′,b′)之间的距离。In formula (5), P _t is the rated power of the charging base station; P(d _ij ) is the charging efficiency between the charging base station and the wireless rechargeable sensor with a distance equal to d _ij , and its expression is

d _ij is the distance between the jth coverage node q _ij of the ith candidate base station c _i and the coordinates (a', b').

d′为候选节点与坐标(a′,b′)的距离。In formula (6), P(d') is the charging efficiency between the charging base station and the wireless rechargeable sensor with a distance equal to d', and its expression is

d' is the distance between the candidate node and the coordinates (a', b').

Proceed to steps 2-7.

则将候选节点作为第i个候选基站c_i的第k+1个覆盖节点q_i,k+1加入第i个候选基站的覆盖节点集合Q_i，将第i个候选基站c_i的坐标更新为(a_i,k+1,b_i,k+1)，a_i,k+1＝a′，b_i,k+1＝b′；将k增大1，并进入步骤2-8。2-7, if

Then the candidate node is added to the coverage node set Qi of the _ith candidate base station as the k+1 th covering node qi of the ith candidate base station c _{i , and k+1} is added to the set of covering nodes Qi of the ith candidate base station, and the coordinates of the ith candidate base station _ci are updated. is (a _i,k+1 ,b _i,k+1 ), a _i,k+1 =a', b _i,k+1 =b'; increase k by 1, and go to step 2-8.

则直接进入步骤2.8。like

Then go directly to step 2.8.

2-8. If the candidate sensor set CU is an empty set; go to step 3; otherwise, repeat steps 2-4 to 2-7.

Step 3: Remove all ordinary nodes from the ordinary sensor set U in the coverage node set Q _i of the ith candidate base station added to the ordinary sensor set U. Take the coordinates (a _i,k, b _i,k ) as the i-th base station deployment position. If the common sensor set U is not an empty set, increase i by 1, and repeat step 2; otherwise, go to step 4.

Step 4, arranging charging base stations on the deployment positions of the base stations determined in steps 2 and 3.

The beneficial effects that the present invention has are:

1. The present invention gets rid of the constraints of assuming that the base station is in certain fixed areas in the existing method, and according to the location information of the wireless rechargeable sensor in the wireless sensor network, on the premise of ensuring the energy demand of the wireless sensor network, the planning is done as much as possible. The number of base stations may be small, and the specific location of the base station is given, which reduces the charging cost of the entire wireless sensor network and is more in line with the actual application scenario.

2. The present invention improves the effect of the deployment position of the charging base station by calculating the convex hull of each common node, and greatly reduces the amount of calculation.

3. The present invention does not set a fixed charging radius when arranging the charging base station, but introduces the charging time of different wireless rechargeable sensors as a variable. In many existing researches on the deployment of charging base stations, it is assumed that the charging base station has a charging radius. If the distance between the sensor and the base station exceeds the range of this radius, the charging base station cannot charge the sensor. However, in practice, due to the different functions performed by each sensor node, their energy consumption is also different, so the charging radius of the same charging base station for wireless rechargeable sensors with different power consumption is different. The method of simply setting a charging radius cannot reasonably allow the charging base station to include all sensor nodes that can receive energy, resulting in the deployment of redundant charging base stations. Therefore, compared with the prior art, the present invention can further save the charging cost.

4. The present invention adopts a "convergent" wireless charging base station, which has a small radiation area but a long radiation distance, so it can adapt to a sensor network with a larger coverage area and a wider distribution area.

Description of drawings

FIG. 1 is a schematic diagram of the deployment of a charging base station and a wireless rechargeable sensor in the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

The present invention is directed to a charging base station deployment scenario in which all wireless rechargeable sensors in the wireless sensor network are arranged on the same plane. The charging base station set in the present invention is a "converged" charging base station with the same specifications. The radiation area of the "converged" charging base station is very small (similar to laser charging), and only one sensor can be covered and charged at the same time. This "converged" energy emission mode can greatly increase the radiation distance of energy , that is, the wireless charging base station used in the present invention is farther away than other charging base stations. To ensure the energy requirements of all sensors in the sensor network, deploy as few base stations as possible to reduce the charging cost of the entire sensor network. The charging base station is capable of charging wirelessly rechargeable sensors one by one. On the deployment plane of the wireless sensor network, n wireless rechargeable sensors with random and known positions are arranged. The relationship between the charging base station and the wireless rechargeable sensor network is shown in Figure 1. In Figure 1, the star is the wireless rechargeable sensor, and the dot is the wireless rechargeable sensor.

As shown in Figure 1, a fixed-point wireless charging base station deployment method based on convex hull selection is as follows:

Step 1. Establish a plane rectangular coordinate system, and place n common nodes corresponding to the respective positions of the n wireless rechargeable sensors into the plane rectangular coordinate system. The set composed of n ordinary nodes is the ordinary node set U={u ₁ , u ₂ , u ₃ , . . . , u _n }. Assign 1 to i. i represents the ordinal number of the charging base station.

Step 2: Find the deployment position of the candidate base station, and determine the coverage node set of the candidate base station.

2-1. Establish a candidate base station set S _i that is initially an empty set. A candidate sensor set CU is established. The candidate sensor set CU, let the candidate sensor set CU be equal to the common node set U.

2-2. According to the coordinates of each ordinary node in the candidate sensor set CU, obtain the convex hull of the candidate sensor set CU (the convex hull is the set of all vertices of the convex polygon, and all the vertices in the convex hull are in the candidate sensor set CU; All ordinary nodes in the ordinary node set U are not outside the convex polygon). Assign 1 to k. k represents the ordinal number of the sensors covered in the i-th charging base station.

2-3. Randomly select one of the vertices of the convex hull obtained in step 2-2 as the first covering node qi _,1 of the ith candidate base station c _i , and add it to the covering node set Qi of the _ith candidate base station . And remove the first coverage node q _i,1 of the i-th candidate base station c _i from the candidate sensor set CU. The coordinates of the first coverage node q _i,1 of the i-th candidate base station c _i are ( _xi,1 ,y _i,1 ). The position of the first coverage node qi _,1 of the ith candidate base station c _i is taken as the initial position of the ith candidate base station. The coordinates of the initial position of the ith candidate base station are (ai _,1, b _i,1 ), a _i,1 = _xi,1 , and b _i,1 =y _i,1 .

2-4. Take the common node that is closest to the i-th candidate base station c _i (coordinates (a _i,k ,b _i,k )) in the candidate sensor set CU as a candidate node. The coordinates of the candidate nodes are (x', y'). Remove the candidate node from the candidate sensor set CU.

2-5. Calculate the base station update prediction coordinates (a', b'); wherein, the expression of a' is shown in formula (1); the expression of b' is shown in formula (2);

η为充电基站与无线可充电传感器紧挨在一起时的传输效率，若未进行充电基站与无线可充电传感器紧挨在一起时检测传输效率，则η用1替代；α的取值为

G_t为充电基站的发射天线的增益大小；G_r为无线可充电传感器的接收天线的增益大小；λ为充电基站与无线可充电传感器进行无线传输时所用电磁波的波长。In formulas (1) and (2), a _i,k is the abscissa before the k-th update of the i-th candidate base station c _i ; b _i,k is the i-th candidate base station c _i before the k-th update is performed. ordinate; w _i,j represents the power of the wireless rechargeable sensor corresponding to the jth coverage node q _i, j of the ith candidate base station c _i ; x _i,j is the jth of the ith candidate base station c _i The abscissa of each coverage node qi _,j ; y _{i,j is} the ordinate of the jth coverage node qi,j of the ith candidate base station c _i ; w' is the power of the wireless rechargeable sensor corresponding to the candidate node ; the value of β is

η is the transmission efficiency when the charging base station and the wireless rechargeable sensor are next to each other. If the transmission efficiency is not detected when the charging base station and the wireless rechargeable sensor are next to each other, η is replaced by 1; the value of α is

G _t is the gain of the transmitting antenna of the charging base station; G _r is the gain of the receiving antenna of the wireless rechargeable sensor; λ is the wavelength of the electromagnetic wave used in the wireless transmission between the charging base station and the wireless rechargeable sensor.

如式(3)所示；2-6. Calculate the charging dormancy duration of the ith candidate base station c _i that is recorded as a candidate node

As shown in formula (3);

In formula (3), T is the charging cycle of the charging base station, and its value is equal to the minimum value of the battery life of n wireless rechargeable sensors, and its expression is shown in formula (4). t _i,j is the charging time of the j-th coverage node of the i-th candidate base station c _i (charging with a charging base station, the time from no power to fully charged), its expression is shown in Equation (5) . t' is the charging duration of the candidate node, and its expression is shown in equation (6).

In formula (4), CM is the battery capacity of each wireless rechargeable sensor. w _max is the power of the sensor with the highest power among the wireless rechargeable sensors.

d_ij为第i个候选基站c_i的第j个覆盖节点q_ij与坐标(a′,b′)之间的距离。In formula (5), P _t is the rated power of the charging base station; P(d _ij ) is the charging efficiency between the charging base station and the wireless rechargeable sensor with a distance equal to d _ij , and its expression is

d _ij is the distance between the jth coverage node q _ij of the ith candidate base station c _i and the coordinates (a', b').

d′为候选节点与坐标(a′,b′)的距离。In formula (6), P(d') is the charging efficiency between the charging base station and the wireless rechargeable sensor with a distance equal to d', and its expression is

d' is the distance between the candidate node and the coordinates (a', b').

则将候选节点作为第i个候选基站c_i的第k+1个覆盖节点q_i,k+1加入第i个候选基站的覆盖节点集合Q_i，将第i个候选基站c_i的坐标更新为(a_i,k+1,b_i,k+1)，a_i,k+1＝a′，b_i,k+1＝b′；将k增大1，并进入步骤2.8。2-7. If the i-th candidate base station c _i is recorded as the charging sleep duration of the candidate node

Then the candidate node is added to the coverage node set Qi of the _ith candidate base station as the k+1th covering node qi of the ith candidate base station c _{i , and k+1} is added to the set of covering nodes Qi of the ith candidate base station, and the coordinates of the ith candidate base station _ci are updated. is (a _i,k+1, b _i,k+1 ), a _i,k+1 =a', b _i,k+1 =b'; increase k by 1, and go to step 2.8.

则直接进入步骤2.8。If the i-th candidate base station c _i is recorded in the charging sleep duration of the candidate node

Then go directly to step 2.8.

2-8. If the candidate sensor set CU is an empty set; go to step 3; otherwise, repeat steps 2-4 to 2-7.

Step 3: Remove all ordinary nodes from the ordinary sensor set U in the coverage node set Q _i of the ith candidate base station added to the ordinary sensor set U. Take the coordinates (a _i,k ,b _i,k ) as the i-th base station deployment position. If the common sensor set U is not an empty set, increase i by 1, and repeat step 2; otherwise, go to step 4.

Step 4, arranging charging base stations on the deployment positions of the base stations determined in steps 2 and 3.

Claims (1)

1. A fixed point wireless charging base station deployment method based on convex hull selection is characterized in that: step 1, establishing a planar rectangular coordinate system, and placing n common nodes corresponding to the respective positions of n wireless chargeable sensors into the planar rectangular coordinate system; a set formed by n common nodes is a common node set U; assigning 1 to i;

step 2, solving the deployment positions of the candidate base stations, and determining a coverage node set of the candidate base stations;

2-1, establishing a candidate base station set S which is initially an empty set_i(ii) a Establishing a candidate sensor set CU, and enabling the candidate sensor set CU to be equal to the common node set U;

2-2, solving a convex hull of the candidate sensor set CU according to the coordinates of each common node in the candidate sensor set CU, and assigning 1 to k;

2-3, selecting one vertex of the convex hull obtained in the step 2-2 as the ith candidate base station c_i1 st overlay node q_i,1Adding a coverage node set Q of the ith candidate base station_iPerforming the following steps; the ith candidate base station c_i1 st overlay node q_i,1Removing from the candidate sensor set CU; ith candidate base station c_i1 st overlay node q_i,1Has the coordinates of (x)_i,1,y_i,1) (ii) a With the ith candidate base station c_i1 st overlay node q_i,1As the initial position of the ith candidate base station; the coordinates of the initial position of the ith candidate base station are (a)_i,1,b_i,1)，a_i,1＝x_i,1，b_i,1＝y_i,1；

2-4, taking the coordinates (a) in the candidate sensor set CU_i,k,b_i,k) The common node with the nearest distance is used as a candidate node; the coordinates of the candidate node are (x, y); removing the candidate node from the candidate sensor set CU;

2-5, calculating the updated predicted coordinates (a ', b') of the base station; wherein the expression of a' is shown as formula (1); the expression of b' is shown as formula (2);

in formulae (1) and (2), w_i,jRepresents the ith candidate baseStation c_iOf the jth overlay node q_i,jPower of a corresponding wireless chargeable sensor; x is the number of_i,jIs the ith candidate base station c_iOf the jth overlay node q_i,jThe abscissa of (a); y is_i,jIs the ith candidate base station c_iOf the jth overlay node q_i,jW' is the power of the wireless chargeable sensor corresponding to the candidate node, and β is the value

η is the transmission efficiency when the charging base station and the wireless chargeable sensor are close together, α is the value

G_tThe gain of a transmitting antenna of the charging base station is increased; g_rThe gain of a receiving antenna of the wireless chargeable sensor is large or small; lambda is the wavelength of electromagnetic waves used when the charging base station and the wireless chargeable sensor carry out wireless transmission;

2-6, calculating the ith candidate base station c_iIs logged into the charge dormancy duration of the candidate node

As shown in formula (3);

in the formula (3), T is a charging period of the charging base station, and an expression of T is shown in the formula (4); t is t_i,jIs the ith candidate base station c_iThe charging duration of the jth coverage node of (1) is expressed by the formula (5); t' is the charging duration of the candidate node, and the expression is shown in the formula (6);

in formula (4), CM is the battery capacity of each wireless chargeable sensor; w is a_maxFor each wireless deviceThe power of the most powerful of the charge sensors;

in the formula (5), P_tRated power for the charging base station; p (d)_ij) Is that the spacing is equal to d_ijThe charging efficiency between the charging base station and the wireless chargeable sensor is expressed as

d_ijIs the ith candidate base station c_iOf the jth overlay node q_ijThe distance from the coordinates (a ', b');

in the formula (6), P (d ') is the charging efficiency between the charging base station and the wireless chargeable sensor with the distance equal to d', and the expression is

d ' is the distance between the candidate node and the coordinates (a ', b ');

entering the step 2-7;

2-7, if

The candidate node is taken as the ith candidate base station c_i(k + 1) th overlay node q_i,k+1Set of coverage nodes Q for joining ith candidate base station_iThe ith candidate base station c_iIs updated to (a)_i,k+1,b_i,k+1)，a_i,k+1＝a′，b_i,k+1B'; increasing k by 1 and proceeding to step 2-8;

if it is

Directly entering the step 2-8;

2-8, if the candidate sensor set CU is an empty set; entering step 3; otherwise, repeating the steps 2-4 to 2-7;

step 3, adding the coverage node set Q of the ith candidate base station into the common node set U_iRemoving all common nodes from the common node set U; in terms of coordinates (a)_i,k,b_i,k) As the ith base station deployment location; if the common node set U is not an empty set, increasing i by 1, and repeatedly executing the step 2; otherwise, entering step 4;

and 4, arranging a charging base station at each base station deployment position determined in the steps 2 and 3.

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