A localization error by the multilateration-based localization algorithm is considerably affected by an accuracy of the A2N distance estimation.
1) First is to improve the accuracy of the A2N distance estimation;  proposed algorithms that improve the accuracy of the average hop length through they approached it differently.
Authors at  proposed schemes to select anchors which can estimate the A2N distance accurately.
*  used the fact that the accuracy of A2N distance estimation becomes lower, when the shortest hop path is a heavily curved shape.
Resultantly, after thorough study of these previous works, we have found that 1) the localization accuracy can be improved when a normal node utilizes a few reliable anchors instead of utilizing all the anchors, 2) the accuracy of the A2N distance estimation and the geometrical shape formed by anchors are important in selecting the reliable anchors.
The proposed localization algorithm consists of two steps: 1) A2N distance estimation, and 2) localization.
On the other hand, the RARL algorithm considers the A2N distance estimation accuracy and the geometric shape formed by the anchors unlike the 4-Nearest Anchor, thus it shows stable and lower localization error than DV-Hop and 4 Nearest Anchor.