In wideband localization systems based on time of arrival (ToA), RF nonideality, such as carrier phase noise, IQ imbalance, phase and frequency offset, plays an important role for ToA estimation accuracy. In this work, Cramer-Rao lower bound (CRB) for ToA estimation in the presence of RF nonideality is first proposed as criterion for ToA estimator performance in practical ToA localization system. Evaluation of CRB with and without phase noise has been performed, especially closed form of CRB without phase noise has been derived. Theoretical and numerical results show that the ToA accuracy presents floor
phenomenon in the presence of RF nonideality, and phase noise plays the dominant role. The effect of record length has also been evaluated.
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