A comparison between time and frequency domain TOA estimators compliant with the 802.15.4a Standard has been made. The time domain estimator is done in two stages. One has the goal of identify the rst pulse in each symbol interval and the other aims to acquire the start of frame delimiter. The frequency domain estimator is also based in two stages. A simple coarse estimation stage provides the symbol synchronization required by the ne estimation stage which nds the rst delay of the rst arriving path in a power delay pro le developed in the frequency domain by using high resolution spectral estimation techniques. An accuracy of few centimeters is asymptotically achieved by both estimators. While time domain estimator shows slightly more accurate results at high values of SNR, frequency domain estimators works slightly better at low SNR.1