Adaptive filter theory (2nd ed.)
Adaptive filter theory (2nd ed.)
Unitary ESPRIT: how to obtain increased estimation accuracy with areduced computational burden
IEEE Transactions on Signal Processing
| Hi-index | 0.00 |
This paper compares algorithms from three different classes ofadaptation schemes for smart antennas – the switched beam approach, aTemporal-Reference (TR) technique based on Direct Matrix Inversion or LeastSquares adaptation, and a Spatial-Reference (SR) technique with directionfinding by Unitary ESPRIT.The simulations are based on a channel modelincluding directions of arrival (DOA) and flat Rayleigh fading. The fadingsignal is spread out in angle over several degrees dependent on the distanceof the mobile from the base station. The results indicate that, in theuplink, TR algorithms and SR algorithms perform equally well, given perfectsynchronization and successful user identification (for SR algorithms). TRalgorithms are the most robust against close-by interference. For a UniformLinear Array (ULA) with M=8 elements and an element spacing ofd equal to half a wavelength, they are able to separate twoco-channel users that are as close as 5 degrees in angle. Foran angular threshold as low as 10° an 8-element ULA isalso sufficient to obtain nearly the same BER performance as for a singleuser.As concerns SR algorithms, we demonstrate their applicability tosituations where no discrete DOAs exist, as it is the case in mobilecommunications. Mutual coupling of individual antenna elements increases theBER by an order of magnitude for the switched beam approach and for SRalgorithms, in contrast to TR algorithms, where the influence of mutualcoupling on the BER is negligible.