Optimization of Self-Directed Target Coverage in Wireless Multimedia Sensor Network

Algorithm 3

Algorithm of single-node multi-interested target self-direction optimal coverage.

Input: multimedia sensor node 𝑠_𝑖, interested target set 𝑇, sensing radius 𝑅_𝑠, FoV vertex angel 𝜃, sensing direction 𝑠_𝑖𝐶

Output: 𝐶_TSET(𝑠_𝑖), TSET as covered goal set after node self-direction opitimization

Define RotateDirection; // rotated direction of node, value as CLOCKWISE or ANTICLOCKWISE

Define RotateAngle; // rotated angel of node

Const N; //number of interested target

Let TSC=Ø; // for angel between node sensing direction to all targets in target set 𝑇

Let CHA[𝑁][𝑁]={0}; // two-dimensional array, for difference among elements in some limit or not.

Let TSET=Ø;

FOR each 𝑇_𝑘∈𝑇

  Calculate ∠𝑇_𝑘𝑠_𝑖𝐶; // angel between sensing direction 𝑠_𝑖 to interested target 𝑇_𝑘

   TSC=TSC∪∠𝑇_𝑘𝑠_𝑖𝐶

END

𝜗;

Sorting TSC from minimal to maximal;

Calculate the difference absolute value between every two elements in TSC. If the difference

absolute value less than or equal to 𝜃, then set CHA corresponding element as 1;

All elements, which numerical of every line is 1 in top triangle of Matrix CHA, constitute the set

with absolute value less than or equal to 𝜃;

Chose the line with maximal numerical equal to 1 in top triangle of Matrix CHA and put

corresponding nodes into set TSET;

Form subset TSETTSC corresponding to set TSC based on the covered target set TSET;

Calculate the mean of maximum and minimum in TSETTSC and recorded as 𝜗

IF 0<𝜗≤𝜋 THEN

  RotateDirection = anticlockwise;

  RotateAngle = 𝜗;

END

IF 𝜋<𝜗<2𝜋 THEN

  RotateDirection = clockwise;

  RotateAngle = 2𝜋−𝜗;

END

ROTATE(𝑠_𝑖, RotateDirection, RotateAngle);

𝐶_TSET(𝑠_𝑖)=1;

RETURN 𝐶_TSET(𝑠_𝑖)TSET