While     (the target is in the detecting area of L-shaped sensor arrays)
If  (it’s the first moment the arrays detect)
        (1) Use all the sensor arrays to sample the signal of the target.
        (2) Calculate the position of the target by maximum likelihood algorithm.
        (3) Select three sensor arrays which are nearest to the targets.
        (1) Use the selected three sensor arrays to sample the signal.
        (2) Get the location by ML algorithm.
If  (the number of the measured position for the target <4)
         The value achieved by ML algorithm is regarded as the final position.
        (1) Use ARPF algorithm to predict the position of the target at the next moment.
        (2) If (the number >4)
        Use the predicted position to guide targets’ localization process which is discussed in Section 4.
Algorithm 1