Estimation of the Number of Multipath Components in a Delay-Dispersive Environment for LTE OFDM Downlink
Student thesis: Master Thesis and HD Thesis
- Vincenzo Malta
10. term, Elektronik og IT, Kandidatuddannelsen (Spec. Signal and Information Processing for Communication) (Master Programme)
Orthogonal Frequency Division Modulation (OFDM) is the modulation employed by the LTE downlink physical layer. Recent studies on pilot-aided channel estimation, typical of such modulation, show that assuming a parametric channel model can effectively improve the estimate accuracy. The algorithms based on this model perform the frequency response estimation of a multipath environment through the knowledge of the tap-delay parameters, i.e., the delays’ values and their number. This thesis focuses on the estimation of the number of delays, required by the tap-delay estimators, e.g., ESPRIT. For this purpose the state-of-the-art MDL detection scheme is investigated over one of the proposed LTE channels and over a dynamic channel. Furthermore, it is compared with an approach based on a simple threshold operation. The study has carried out jointly with the preprocessing scheme named spatial smoothing. It’s shown that over the static channel, MDL exhibits a certain robustness against the time observation reduction, while the Threshold algorithm suffers from a significant increase in the estimate’s error. Tests over the dynamic channel show a general performances decrement. However MDL average error keeps constant within a wide window size range and it doesn’t drastically get worse as the Threshold one. The state-of-the-art performances then, are not exceeded, but the noticed problems still leave this topic open.
Language | English |
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Publication date | 2010 |
Number of pages | 89 |
Publishing institution | Aalborg University |