Localization for Wireless Sensor Networks Assisted by Two Mobile Anchors with Improved Grey Wolf Optimizer

Algorithm 2

Location estimation of

Input: , ,

Output:

1.  the virtual anchor with the largest RSSI in

2.  the virtual anchor with the second-largest RSSI in

3.  If ( satisfying is an equilateral triangle)

4.   

5.  Else

6.   the virtual anchor with the third-largest RSSI in

7.  End if

8.  Get by eq. (26)

9.  

10.  Initialize a grey wolf population in

11.  Initialize , , and by Eq. (14), Eq. (15), Eq. (20), and Eq. (25)

12.  Calculate the fitness of each wolf by Eq. (3)

13.  the best wolf

14.  the second-best wolf

15.  the third-best wolf

16.  

17.  While

18.   For each wolf

19.    Get by Eq. (19)

20.    a random number in [0,1]

21.    If

22.     Get by Eq. (21)

23.     Get the final by Eq. (22)

24.    Else if

25.     Get by Eq. (23)

26.     Get the final by Eq. (24)

27.    End if

28.   End for

29.   Update , , and by Eq. (14), Eq. (15), Eq. (20), and Eq. (25)

30.   Calculate the fitness of each wolf by Eq. (3)

31.   Update , and

32.   

33.  End while

34.  Return