In this paper, several novel algorithms for improving the localization results of unknown wireless nodes are presented. All introduced algorithms extend the concept of Universal Improvement Scheme (UnIS) presented in our previous publications [1], [2]. We describe the algorithms using mathematical models and show with simulation results the effectiveness of new solutions in comparison to previous approaches. Additionally, we prove the simulations with real testbed evaluation results obtained with a wireless sensor network consisting of 3 prepositioned reference nodes (anchors) and 10 unknown nodes (mobiles). The introduced testbed was placed indoor and was build using ZEBRA2411 modules from senTec Elektronik GmbH, based on the chipset ZRP1 developed by Freescale Semiconductor [3].