Accurate indoor localization is a key component for many applications such as tracking, indoor navigation, home/industrial automation, gaming and intelligent transportation systems. Impulse radio ultrawide-band (IR-UWB) allows sub-meter accurate localization due to its inherent high time resolution. The accuracy of localization depends on the detection moment of the direct path signal (Time Of Arrival: TOA). Many studies focus only on TOA estimation without providing a close to system approach. Unlike these studies, we provide a system compatible solution which takes into account low resources design constraints. In this paper, a) we propose a design for sub-meter localization using 802.15.4a UWB compliant signals, b) we integrate our design in a real localization system and c)we evaluate its accuracy in a real scenario. The proposed design is robust to multipath environment by being on the fly adjustable to the existing channel properties. It accomplishes high accuracy and it is ideal for limited resource systems, meeting the low resources requirements of IEEE 802.15.4a standard. The measured error is around 5-10 cm in a multipath environment for 1 GHz sampling rate. This work is novel and it tries to bridge the gap between theoritical digital signal processing solutions presented in literature and the feasibility of a low cost implementation for sensor nodes.