Channel Estimation Methods in Carrier Aggregation OrthogonalFrequency Division Multiplexing Systems
| Autor: | Min-Yu Wang, 王旻祐 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In this thesis, we will investigate advances of signal processing techniques for subspace-based blind and pilot-assisted channel estimation in carrier aggregation (CA) orthogonal frequency division multiplexing (OFDM) systems. Carrier aggregation is one of the most distinct features of 4G systems including LTE Advanced, which is being standardized in 3GPP as part of LTE Release 10. This feature allows scalable expansion e ective bandwidth delivered to increase overall data rate. The channel frequency responses of individual component carriers are quiet di erent due to the nature of frequency selective channels induced from multipath environment. But these frequency responses can actually be derived from the same channel impulse response determined by multipath conditions. Based on this property, we propose to take advantage of the correlation present among di erent component carriers of the same physical link. For the initial step to explore this topic, we apply blind channel estimation, which have been largely studied due to high bandwidth e ciency. In communication systems employed with cyclic pre xes (CP), subspace-based (SS) methods are among the most popular categories of blind channel estimation schemes. Since existing blind channel estimation methods are only applied in single frequency band system, the idea of combining data from multiple frequency bands is proposed. Simulation results show that the proposed method outperforms all previously reported methods. Another important problem, namely the pilot-assisted channel estimation, is also studied in this thesis. Pilot-assisted channel estimation method can be divided into two methods: pure pilot-assisted method and semi-blind method. In all previously reported methods, pilot-assisted channel estimation methods are only applied in single component carrier system, we extend the estimation to multiple bands system. Simulation results show that the proposed method outperforms the previous pure pilot-assisted and semi-blind methods with the same number of pilot samples. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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