In wireless OFDM systems, the time-varying channel is often estimated by a Wiener filter-type MMSE estimator based on pilot symbols. Such an estimator, however, requires statistical prior knowledge that is not easily obtained. Here, we propose adaptive Wiener filters for channel estimation that do not require statistical prior knowledge. We also calculate the performance limits of finite-length...

Fix ν > 0, denote by G(ν/2) a Gamma random variable with parameter ν/2 and let n ≥ 2 be a fixed even integer. Consider a sequence {F k } k≥1 of square integrable random variables belonging to the nth Wiener chaos of a given Gaussian process and with variance converging to 2ν. As k → ∞, we prove that F k converges in distribution to 2G(ν/2) − ν if and only if E(F 4 k) − 12E(F 3 k) → 12ν 2 − 48ν.

In the present paper we compute the geometric minimum mean square error for the vector linear estimation problem. We do this by proving that the vector linear estimator that minimizes the mean square error (MSE) also minimizes the geometric MSE.

myocardial perfusion spect imaging with tc99m-sestamibi is the most accurate non-invasive means of detecting coronary artery disease and assessing the severity of perfusion abnormalities in the patients with coronary stenosis. though simple and straight forward the results produced by the technique is very much affected by the details being used. one of the main problems with the test, which ha...