Orthogonal Frequency Division Multiplexing (orthogonal frequency division multiplexing, OFDM) has been widely applied in today's wireless communications. One major reason for the popularity of OFDM systems is that almost half of bandwidth can be saved from traditional systems with subcarriers' orthogonality. The transmitted signals may suffer Carrier Frequency Offsets (CFO), caused by Doppler effects and misadjustment of transmit and receive oscillators, and the orthogonality will be destroyed. The CFO will result Intercarrier Interference (ICI) and degrade the system performance. Therefor, CFO must be estimated accurately to remove the ICI. In 1998, H. Liu and U. Tureli proposed a CFO estimation algorithm based on Multiple Signal Classification (MUSIC)[ 11 ]. This method is blind and can provide hight accuracy. However, it only works in cyclic prefix (CP) OFDM system.
In this thesis, we propose a MUSIC CFO estimation which can be used in zero padding (ZP) OFDM. After appropriate superposition of ZP-OFDM received signals, a CP-like signal can be obtained. Such that the MUSIC algorithm can be applied to ZP-OFDM.A modified singular value decomposition (SVD) channel estimation for ZP-OFDM with full-loaded subcarriers is also proposed in this thesis.
From simulation results, the MUSIC CFO estimation for ZP-OFDM is workable. The performance of CFO estimation depends on the searching interval of the minimization process. Smaller searching results better. In SVD channel estimation, ZP-OFDM with null subcarriers can provide better root-mean-square error performance. The performance of SVD channel estimation is only related to the length of channel path.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0910109-154816 |
| Date | 10 September 2009 |
| Creators | Chin, Ching-Yu |
| Contributors | Jih-ching Chiu, Ju-ya Chen, Ching-piao Hung, Chin-Der Wann |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0910109-154816 |
| Rights | not_available, Copyright information available at source archive |
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