Closed-form Cramér-Rao Bound for envelope-based estimators of the Ricean K-factor

In this paper, an analytical expression of the Cramér-Rao Lower Bound (CRLB) for envelope-based unbiased estimators of the Ricean K-factor is derived. The received signal is modeled by the sum of a Line-Of-Sight (LOS) component and a scattered component. Our new closed-form expression allows the immediate evaluation of the CRLB and corroborates previous works, which are numerically computed from very complex expressions. We also compare the performance of a moment-based estimator with the developed analytical CRLB. Simulation results show that the first and second-order moments-based estimator performance is close to the CRLB while the second and fourth-order moments estimator shows higher estimation error.