The Study of Adaptive Equalization in MIMO-OFDM Systems
| Autor: | Kan-Si Lin, 林耕毅 |
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| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 This thesis presents a decision-feedback adaptive channel-estimation scheme for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems under time-variant frequency-selective fast-fading channels. IEEE 802.11n standard of TGn Sync Proposal is targeted. It operates at 2.4GHz band with 20MHz bandwidth. Both 2 2 and 4 4 transceiver allocations with corresponded Space-Time Block Coding (STBC) are considered. Two time-variant channel models are applied to the simulation platform. One is the well-known Jakes’ model, and the other is a custom model defined on the concept of randomly changed channels. The adaptive equalization contains two parts. First, the proposed adaptive channel estimation scheme is applied to the STBC-decoded symbols in order to estimate the noisy time-variant channels. The second and the last, a frequency domain Wiener filter is applied to each estimated noisy time-variant channel to decrease the Signal-to-Noise Ratio (SNR) requirements that adaptive equalization needed. The proposed algorithm achieves 104Mbps data rate under 120km/hr Jakes’ model at 24dB SNR and 78Mbps for 250km/hr at 20dB SNR for 2 2 MIMO-OFDM systems, and 208Mbps for 4 4 MIMO-OFDM systems under 120km/hr Jakes’ model at 29.5dB SNR. In hardware implementation phase, the frequency domain Wiener filter is omitted since its computational complexity is too high to fit in regular area constrains. The proposed adaptive equalizer for 4 4 MIMO-OFDM systems is a pipelined design and is implemented using UMC 0.13um^2 process. The total gate count of the 4 4 adaptive equalizer is 1.9 million. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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