| Summary: | In a WCDMA transmission systems, the properties of the radio transmissionchannels can be strongly aected by the movement of User Equipment (UE) orthe surrounding objects. The estimation of Doppler spread is therefore of greatimportance since it is closely related to the mobile speed, as it can also be usedto characterize the fast fading in the radio channel. Thus the Doppler spread estimation can have wide range of applications and the relative research on thistopic has drawn much attention. Many Doppler spread estimation algorithms has been proposed in the literature. In this report, these algorithms are divided into four categories, and the comparison is performed from both performanceand implementation point of view to compare these four types of estimators. During the investigation, the Rayleigh fading and Rician fading model withdierent mobile speed and SNR are simulated to analyze the performance of estimation algorithms under dierent conditions. The effect of Rician factor and angle of arrival of Line Of Sight (LOS) component is also taken into consideration in the evaluation. Furthermore, the computational complexity of each algorithm is calculated. Based on simulation results, the underlying reasons for their performances are analyzed individually. The Moser's estimator (correlation based estimator) demonstrates the best performance among these four estimators from the perspective of estimation accuracy. And it also shows the great value for the implementation in real systems. === I ett kommunikationssystem baserat p WCDMA kan egenskaperna hos radiotransmissionskanalernapverkas starkt av mobilens eller omgivningens rrelser.Estimering av Doppler spridningen r drfr av stor betydelse eftersom den r nrabeslktad med mobilens hastighet och den kan ocks anvndas fr att karakteriseraden snabba fdning i radiokanalen. Sledes kan estimat av Dopplerspridning ha ettbrett anvndningsomrde och forskningen om detta mne har varit intesiv. Mngaalgoritmer fr estimatering av Doppler spridning har freslagits i litteraturen. Idenna rapport, dessa algoritmer r indelade i fyra kategorier och analysen utfrsbde med avseende p prestanda och implementerbarhet. Simuleringar r utfrdamed Rayleigh fading och Rician modeller med olika hastigheter hos mobilen,och olika signal till brus frhllanden. Simuleringar har ocks gjorts fr olika vrdenav Ricianfaktorn och vinkel fr inkommande signal. Vidare har den berkningsmssigakomplexiteten av varje algoritm analyserats. Utifrn simuleringsresultathar de bakomliggande orsakerna till de olika algoritmernas prestatandadiskuterats. Dopplerspridningsestimat med Mosers metod (korrelation baseradestimator) visar det bsta resultatet bland dessa fyra estimator med avseendep skattningsnoggrannhet. Denna metod har ven frhllandevis lg berkningskomplexitetvilket gr den implementeringsvnlig.
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