CN103916874B - Wireless sensor network covering method based on polar coordinates - Google Patents

Abstract

The invention discloses a wireless sensor network covering method based on polar coordinates. The method includes the following steps that first, the position of the origin of the polar coordinates is set by a server, and wireless sensor nodes are converted into polar coordinate position information according to the position relation between a rectangular coordinate system and a polar coordinate system; second, the polar coordinate position information of each wireless sensor node is sent to the neighbor nodes by the wireless sensor node; third, according to the position information of the neighbor nodes, the virtual radius of each node requiring to be changed when the node reaches the position tangent with the corresponding neighbor node in the radial direction relative to the neighbor node and the virtual radius of the node requiring to be changed when the node reaches the boundary expectation position are calculated; fourth, each node is moved to a new coordinate position; fifth, the virtual angle of each node requiring to be moved when the perception circle of the node reaches the position tangent with the perception of the corresponding neighbor node in the circumferential direction is calculated, and the position information of each new node is updated; sixth, the operation is ended or the second step is executed again. Through the method, the coverage of a wireless sensor network with the node deployment area being round can be improved.

Description

Based on polar wireless sensor network coverage method

Technical field

The present invention relates to wireless sensor network coverage method, more particularly to it is a kind of based on polar wireless sensor network Network covering method.

Background technology

At present, with the development of sensor network technology and micro-electronic manufacturing, by a large number with perception, computing capability The wireless sensor network constituted with the microsensor node of communication capacity is applied to military field or civil area.Network Covering is one of basic problem of wireless sensor network, and it reflects sensor network nodes and specified monitor area is monitored Degree, have impact on to a great extent the performance of the cost and network of network in various concrete applications.

Wireless sensor network covering algorithm can be divided into target coverage research according to the difference of monitoring objective and region is covered Lid research.In the research of region overlay, it is sufficiently large to be normally set up node deployment region, so as to ignore edge effect or by portion Administration's regioal hypothesis is rectangle.And in reality, wireless sensing net node is shed at random in deployment region, deployment region is with circle most It is close.But circular boundary is complex to the position restriction of node in rectangular coordinate system, and can pass through right in polar coordinate system The restriction of radial coordinate is limited to node location in border circular areas.Generally wireless sensor network has the characteristics that, is covering Before lid algorithm performs, node is accurately positioned, known to node location；Node can move freely on two dimensional surface, it is possible to Accurately move to specified location；Node can be by way of single-hop or multi-hop and base station communication.

The content of the invention

It is an object of the invention to provide a kind of be based on polar wireless sensor network coverage method, it is possible to increase node Deployment region is circular wireless sensor network coverage rate.

The present invention adopts following technical proposals：One kind be based on polar wireless sensor network coverage method, including with Lower step：

（1）, netinit：Wireless sensor node random placement is wireless to pass in the circular monitored area that radius is R Sensor node gets the positional information of rectangular coordinate system by self-contained positioner, and positional information is sent to into clothes Business device；

（2）, server settings polar coordinate system origin position, and it is wireless that origin position information is sent in network into each Sensor node, wireless sensor node according to the position relationship of rectangular coordinate system and polar coordinate system, by itself rectangular coordinate system Positional information is converted into polar coordinate position information；

（3）, each wireless sensor node by broadcast form by itself polar coordinate position information be sent to neighbours section Point, polar coordinate position information includes the polar coordinates radius and angle of node, and each wireless sensor node is according to the information for receiving The number and positional information of the neighbor node of statistics node, while calculating neighbor node to the distance of node itself；

（4）, according to the positional information of neighbor node, calculate the expectation position that egress reaches each neighbor node radial direction The imaginary radius of required change when putting, described neighbor node radial direction desired locations are that node moves beeline along radial direction Reach the position tangent with neighbor node；When the size of described imaginary radius is that the perception of two nodes justifies tangent, node is relative The distance moved needed for neighbor node；And whether decision node intersects with border, so as to calculate node reaches border position is expected The imaginary radius size of change needed for putting；Perception circle and border tangent position of the described border desired locations for node；

（5）, by node relative to all neighbor nodes and border reach needed for desired locations change imaginary radius summation As the distance that actual node is moved radially, and by node motion to new coordinate position；Node is calculated according to polar coordinates Rectangular co-ordinate, and new position is moved to, until by all node motions to new coordinate position, and all sections are broadcasted in a network The new polar coordinate position information of point, information of each node according to the information updating neighbor node for receiving；

（6）, according to the positional information of the neighbor node after renewal, the perception circle for calculating egress reaches in a circumferential direction To perceiving the minimum angles that move needed for the tangent position of circle with neighbor node, and it is node with respect to neighbor node to define this angle Virtual angle；

（7）, successively calculate virtual angle of the egress with respect to each neighbor node, and calculate node all virtual angles Algebraical sum is used as the actual mobile angle of node, the positional information of more new node；Node calculates rectangular co-ordinate according to polar coordinates, And it is moved to new position, until by all node motions to new coordinate position, and the new of all nodes is broadcasted in a network Polar coordinate position information, information of each node according to the information updating neighbor node for receiving；

（8）, calculate actual the moving radially of wireless sensor network interior joint and move apart from absolute value sum and circumferencial direction Angle absolute value sum, if moving radially apart from absolute value sum less than the angle that radius threshold and circumferencial direction are moved Sum is less than angle threshold value, then terminate；If moving radially apart from absolute value sum more than angle threshold value, return to step （2）, continue to iterate to calculate carries out coverage optimization to network.

Described step（4）Interior joint is with respect to the imaginary radius of neighbor node

Δr_ij=r_i-r′_ij；

Wherein,

(r_i,θ_i) it is nodes X_iPolar coordinates, X_jFor nodes X_iNeighbor node, its polar coordinates be (r_j,θ_j), θ_ijIllustrate VectorTo vectorThe anglec of rotation, if Δ r_ij<0, node is moved along radial direction to the polar coordinates center of circle, conversely, then edge Radial direction is moved away from the center of circle.

Described step（4）In the imaginary radius of node retive boundary desired locations be

(r_i,θ_i) it is nodes X_iPolar coordinates, R for wireless sense network circular disposition region radius, r is sensor node The perception radius, when node intersects with zone boundary, Δ r_ie>0, node is moved along radial direction to the polar coordinates center of circle.

Described step（6）In virtual angle delta θ_ij, θ_ijΔ θ when >=0_ijFor β-| θ_ij|；θ_ij<Δ θ when 0_ijFor-(β-| θ_ij|)；Wherein θ_ijFor vectorTo vectorBetween angle, θ_ij∈ (- π, π], β angles are vectorWith vector Angle, β ∈ [0, π).

Described step（8）In radius threshold be：

Angle threshold value is：

ω_r, ω_θFor weighted value, N is the number of wireless senser, ω_r∈ (0,1), ω_θ∈(0,1)。

It is of the present invention to be used to solve to be disposed in border circular areas based on polar wireless sensor network coverage method Wireless sense network covering problem, according to the relation of polar coordinate system and rectangular coordinate system, the position of nodes is converted into Polar coordinate position, counts the relative position relation between neighbor node and node, from radial direction and circumferencial direction both direction pair The position of node is adjusted, according to node ID order successively iteration optimization, and by radius value in node polar coordinate position Limit, the simple and effective overlapping region in deployment region, as far as possible reduced node control between node optimizes network Coverage rate.

Description of the drawings

Fig. 1 is method of the present invention flow chart；

Fig. 2 is that polar coordinates sit transition diagram with right angle；

Fig. 3 is the imaginary radius schematic diagram that relative neighbor node changes（r_j·cosθ_ij>r_i）；

Fig. 4 is the imaginary radius schematic diagram that relative neighbor node changes（r_j·cosθ_ij≤r_i）；

Fig. 5 is the imaginary radius schematic diagram that retive boundary changes；

Fig. 6 is virtual angle schematic diagram.

Specific embodiment

The present invention is by N number of wireless sensor node random placement in the border circular areas that radius is R, by polar Conversion, round overlapping area is perceived as target to reduce between node, adjust the radius of node and the size of angle, improves network Coverage rate.The perception radius of sensor node are r, when the perception circle of two adjacent nodes is tangent in region, the two sections There is no overlapping region in the perception circle of point, now the sensing region utilization rate of two nodes reaches maximum.The position of node is excellent Change is decomposed into radially optimization and the optimization of circumferencial direction, and when radially optimizing, node only can be moved along the line of origin to node, The minimum range of required movement when egress perceives round tangent with neighbor node is calculated, this distance changes for node with respect to neighbor node The imaginary radius of change.Calculate node and obtains vector with respect to the size of the imaginary radius of each neighbor node, used as node edge The actual mobile distance of radius.When circumferencial direction optimizes, the annulus movement that node only can be located along polar coordinate system interior joint is calculated The minimum angles of required movement when egress perceives round tangent with neighbor node, this angle is what node changed with respect to neighbor node Virtual angle, calculate node obtains vector with respect to the size of the virtual angle of each neighbor node, circumferentially square as node To actual mobile angle.As shown in figure 1, the method for the invention specifically includes following steps：

（1）, netinit：Wireless sensor node random placement is wireless to pass in the circular monitored area that radius is R Sensor node gets the positional information of rectangular coordinate system by self-contained positioner, and positional information is sent to into clothes Business device, all wireless sensor nodes can be connected by way of a jump or multi-hop with server wherein in network；

（2）, server settings polar coordinate system origin position, and it is wireless that origin position information is sent in network into each Sensor node, wireless sensor node according to the position relationship of rectangular coordinate system and polar coordinate system, by itself rectangular coordinate system Positional information is converted into polar coordinate position information；

Fig. 2 show the schematic diagram of polar coordinates and rectangular co-ordinate conversion, and 1 is rectangular coordinate system, and 2 is polar coordinate system, and 3 are section Point X_iPerception circle.Coordinates of the polar origin O in rectangular coordinate system is (x_o,y_o), nodes X_iPosition be (x_i,y_i), section Coordinate of the point in polar coordinate system is (r_i,θ_i), wherein

（3）, each wireless sensor node by broadcast form by itself polar coordinate position information be sent to neighbours section Point, polar coordinate position information includes the polar coordinates radius and angle of node, and each wireless sensor node is according to the information for receiving The number and positional information of the neighbor node of statistics node, while calculating neighbor node to the distance of node itself；

（4）, according to the positional information of neighbor node, calculate the expectation position that egress reaches each neighbor node radial direction The imaginary radius of required change when putting, described neighbor node radial direction desired locations are that node moves beeline along radial direction Reach the position tangent with neighbor node；When the size of described imaginary radius is that the perception of two nodes justifies tangent, node is relative The distance moved needed for neighbor node；

If Fig. 3, Fig. 4 are size of the different situations lower node with respect to the imaginary radius that neighbor node changes.Solid line circle 1 is represented Neighbor node X_jPerception circle position, solid line circle 2 represent nodes Xs_iPerception circle position, point 3 represent nodes Xs_iCounterpart node X_j's Desired locations, broken circle 4 represents nodes X_iCounterpart node X_jDesired locations on perceive round position.Make θ=| θ_j-θ_i|, vectorWith vectorBetween angle be：

Neighbor node is to nodes X on radial direction_iThe polar coordinates radius of desired locations be：

Nodes X_iWith respect to neighbor node X_jThe imaginary radius of change are：

Δr_ij=r′_i-r_ij；

If Δ r_ij<0, nodes X_iDo virtual movement to polar origin along radial direction, conversely, then along radial direction away from Origin does virtual movement.

（5）, decision node whether intersect with border, so as to calculate node reach border desired locations needed for change it is virtual Radius size；Perception circle and border tangent position of the described border desired locations for node；

As shown in figure 5, solid line circle 1 represents nodes X_iPerception circle position, broken circle 2 represent nodes X_iThe phase of retive boundary Hope on position and perceive round position.By polar origin and nodes X_iIt is connected with straight line, connecting line meets at a point E with border_i, section Point X_iTo point E_iDistance be less than the perception radius r, node need to along polar coordinates radial direction to origin move Δ r_ieDistance, reach The desired locations of retive boundary.

（6）, node is reached the imaginary radius summation changed needed for all neighbor nodes and border desired locations as reality The distance that border node is moved radially：

Node motion is to new coordinate position (r_i′,θ_i),

r_i′=r_i+Δr_i；

Until by all node motions to new coordinate position, and the new coordinate position of all nodes is broadcasted in a network Information, information of each node according to the information updating neighbor node for receiving；

（7）, according to the neighbor node positional information after renewal, the perception circle for calculating egress reaches in a circumferential direction Perceive the minimum angles move needed for the tangent position of circle with neighbor node, and it is node with respect to neighbor node to define this angle Virtual angle；

The schematic diagram of virtual angle is illustrated in figure 6, solid line circle 1 represents neighbor node X_jPerception circle position, solid line circle 2 Represent nodes X_iPerception circle position, point 3 represent nodes Xs_iCounterpart node X_jDesired locations.Angle 4 is θ_ijRepresent vector To vectorBetween angle, θ_ij∈ (- π, π], angle 5 represents vector for βWith nodes X_iThe vector that desired locations are locatedAngle β ∈ [0, π), angle 6 be Δ θ_ijRepresent nodes X_iCounterpart node X_jThe virtual angle for changing.

Can be obtained according to the division property of vector, θ_ijFor vectorPhase angle.

|Δθ_ij|=β-|θ_ij|；

If θ_ij>0, then it is vectorialTo vectorTurn clockwise, conversely, vectorialTo vectorNeed the inverse time Pin rotates.Therefore Δ θ_ijIt is expressed as following formula：

（8）, successively calculate virtual angle of the egress with respect to each neighbor node, and calculate node all virtual angles Algebraical sum is used as the actual mobile angle of node

The positional information of more new node；θ_i′=θ_i+Δθ_i。

Until by all node motions to new coordinate position, and the new coordinate position of all nodes is broadcasted in a network Information, information of each node according to the information updating neighbor node for receiving；

（9）, calculate actual the moving radially of wireless sensor network interior joint and move apart from absolute value sum and circumferencial direction Angle absolute value sum, if moving radially apart from absolute value sum less than the angle that radius threshold and circumferencial direction are moved Sum is less than angle threshold value, then terminate；If moving radially apart from absolute value sum more than angle threshold value, return to step （2）, continue to iterate to calculate carries out coverage optimization to network.

Described radius threshold is：

Angle threshold value is：

ω_r, ω_θFor weighted value, N is the number of wireless senser, ω_r∈ (0,1), ω_θ∈(0,1)。

Claims (5)

1. It is 1. a kind of to be based on polar wireless sensor network coverage method, it is characterised in that：Comprise the following steps：

   (1), netinit：Wireless sensor node random placement radius for R circular monitored area in, wireless senser Node gets the positional information of rectangular coordinate system by self-contained positioner, and positional information is sent to into service Device；

   (2), the position of server settings polar coordinate system origin, and origin position information is sent to into each wireless sensing in network Device node, wireless sensor node according to the position relationship of rectangular coordinate system and polar coordinate system, by itself rectangular coordinate system position Information is converted into polar coordinate position information；

   (3), itself polar coordinate position information is sent to neighbor node, pole by each wireless sensor node by the form broadcasted Co-ordinate position information includes the polar coordinates radius and angle of node, and each wireless sensor node is according to the Information Statistics section for receiving The number and positional information of the neighbor node of point, while calculating neighbor node to the distance of node itself；

   (4), according to the positional information of neighbor node, calculate egress and reach and neighbor node in radial direction with respect to each neighbor node The imaginary radius of required change during tangency location, the size of described imaginary radius be two nodes perception circle it is tangent when, node Relative to the distance moved needed for neighbor node；And whether decision node intersects with border, so as to calculate node reaches the border phase Hope the imaginary radius size changed needed for position；Perception circle and border tangent position of the described border desired locations for node Put；

   (5), using node relative to all neighbor nodes and border reach needed for desired locations change imaginary radius summation as The distance that actual node is moved radially, and by node motion to new coordinate position；Node calculates right angle according to polar coordinates Coordinate, and new position is moved to, until by all node motions to new coordinate position, and all nodes are broadcasted in a network New polar coordinate position information, information of each node according to the information updating neighbor node for receiving；

   (6), according to the positional information of the neighbor node after renewal, calculate egress perception circle reach in a circumferential direction with Neighbor node perceives the minimum angles moved needed for the tangent position of circle, and it is void of the node with respect to neighbor node to define this angle Intend angle；

   (7), virtual angle of the egress with respect to each neighbor node is calculated successively, and the algebraically of all virtual angles of calculate node With the angle as the actual movement of node, the positional information of more new node；Node calculates rectangular co-ordinate according to polar coordinates, and moves Move to new position, until by all node motions to new coordinate position, and the new pole seat of all nodes is broadcasted in a network Cursor position information, information of each node according to the information updating neighbor node for receiving；

   (8), calculating wireless sensor network interior joint is actual moves radially the angle moved apart from absolute value sum and circumferencial direction Degree absolute value sum, if move radially being less than the angle sum that radius threshold and circumferencial direction are moved apart from absolute value sum Less than angle threshold value, then terminate；If moving radially apart from absolute value sum more than angle threshold value, return to step (2), after Continuous iterative calculation carries out coverage optimization to network.
2. 2. according to claim 1 based on polar wireless sensor network coverage method, it is characterised in that：Described Step (4) interior joint is with respect to the imaginary radius of neighbor node

   Δr_ij=r_i-r′_ij；

   Wherein,

   $r_{ij}^{\&prime;}=\left\{\begin{array}{cc}{r}_j{\mathrm{cos\&theta;}}_{ij}-\sqrt{4r^2-{(r_j\&CenterDot;{\mathrm{sin\&theta;}}_{ij})}^2}& r_j\&CenterDot;{\mathrm{cos\&theta;}}_{ij}>r_i\\ r_j{\mathrm{cos\&theta;}}_{ij}+\sqrt{4r^2-{(r_j\&CenterDot;{\mathrm{sin\&theta;}}_{ij})}^2}& r_j\&CenterDot;{\mathrm{cos\&theta;}}_{ij}\&le;r_i\end{array}\right.;$

   (r_i,θ_i) it is nodes X_iPolar coordinates, X_jFor nodes X_iNeighbor node, its polar coordinates be (r_j,θ_j), θ_ijIllustrate vectorTo vectorThe anglec of rotation, if Δ r_ij<0, node is moved along radial direction to the polar coordinates center of circle, conversely, then along radius Move away from the center of circle in direction.
3. 3. according to claim 1 based on polar wireless sensor network coverage method, it is characterised in that：Described The imaginary radius of the node retive boundary desired locations in step (4) are

   ${\mathrm{\&Delta;r}}_{ie}=\left\{\begin{array}{cc}r-R+r_i& r_i+r>R\\ 0& r_i+r\&le;R\end{array}\right.;$

   (r_i,θ_i) it is nodes X_iPolar coordinates, R for wireless sense network circular disposition region radius, r for sensor node sense Know radius, when node intersects with zone boundary, Δ r_ie>0, node is moved along radial direction to the polar coordinates center of circle.
4. 4. according to claim 1 based on polar wireless sensor network coverage method, it is characterised in that：Described Virtual angle delta θ in step (6)_ij, θ_ijΔ θ when >=0_ijFor β-| θ_ij|；θ_ij<Δ θ when 0_ijFor-(β-| θ_ij|)；Wherein θ_ijFor VectorTo vectorBetween angle, θ_ij∈ (- π, π], β angles are vectorWith vectorAngle, β ∈ [0, π)。
5. 5. according to claim 1 based on polar wireless sensor network coverage method, it is characterised in that：Described Radius threshold in step (8) is：

   $r_{th}=\frac{2{\mathrm{\&omega;}}_{r}arctan\frac{N}{2{\mathrm{\&pi;R}}^2}}{\mathrm{\&pi;}}\&CenterDot;r;$

   Angle threshold value is：

   ${\mathrm{\&theta;}}_{th}=\frac{2{\mathrm{\&omega;}}_{\mathrm{\&theta;}}arctan\frac{N}{2{\mathrm{\&pi;R}}^2}}{\mathrm{\&pi;}}\&CenterDot;\mathrm{\&pi;}=2{\mathrm{\&omega;}}_{\mathrm{\&theta;}}arctan\frac{N}{2{\mathrm{\&pi;R}}^2};$

   ω_r, ω_θFor weighted value, N is the number of wireless senser, ω_r∈ (0,1), ω_θ∈(0,1)。