碩士 / 國立暨南國際大學 / 通訊工程研究所 / 96 / Due to the rapid development of transceiving techniques, high transmission data rate, efficient spectral bandwidth, and quality of reliability are more necessary for future wireless communications systems. Orthogonal frequency division multiplexing (OFDM) schemes are a well-known wireless transmission technique which is effective against frequency selective fading channel and capable of reducing multipath propagation effects very well. Multi-input multi-output (MIMO) architectures can provide multiple artificial uncorrelated channels for transmitting/receiving replicas of the same signals simultaneously through various antennas at different symbol duration to obtain diversity gains.
For MIMO-OFDM systems, channel estimation is crucial for the decoding procedure of space-time block coding (STBC) to separate the superposition results from multiple transmitted signals. In order to compensate the signal distortion, pilot-symbol-assisted channel estimation (PSACE) techniques with various pilot assignments have been used to obtain the channel impulse response (CIR). In practice, the channel estimation procedure can be assisted by transmitting pilot symbols that are already known at the receiver end. Therefore, system performance with channel estimation usually depends on the choice of pilot patterns and the number of pilot symbols.
In this thesis, three kinds of channel estimation algorithms are developed with various pilot assignments for STBC-based MIMO-OFDM systems. They are (1) inner product estimation with non-zero pilots (M1), (2) inner product estimation with virtual pilots (M2) and (3) least squares estimation with virtual pilots (M3). All of three estimation algorithms utilize orthogonal pilot patterns between Tx.1 and Tx.2. The performances of M2 and M3 are almost identical. If there are more antennas on transmitter end, M3 is easier to implement than M1. Therefore, the estimation algorithm in M3 is not only to reduce computation complexity but also to obtain better system performance. Finally, some comparative simulations are given to illustrate the superior performance of M3 in STBC-based MIMO-OFDM systems under COST 207 mobile wireless environments.
| Identifer | oai:union.ndltd.org:TW/096NCNU0650003 |
| Date | January 2008 |
| Creators | Shin-Yan Huang, 黃新喭 |
| Contributors | Jung-Shan Lin, 林容杉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 89 |
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