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| Subspace-Tracking Channel Estimation for Pilot-Symbol-Aided
OFDM Systems with Transmitter Diversity |
| Xu Xin; Cai Yue-ming; Bai Bin-feng; Xu You-yun |
| Institute of Communications Engineering, PLAUST, Nanjing 210007, China |
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Abstract Transmitter diversity has been studied extensively as a technique for combating channel fading in mobile wireless communications, especially when receiver diversity is expensive or impractical. In this paper, three subspace-tracking channel estimation algorithms for OFDM systems with transmitter diversity are proposed, and their performances are compared. Because the fading channel has slow-varying delays and fast-varying amplitudes, the noise effect in the channel estimation can be partially eliminated by tracking delay subspace and amplitudes of the channel. In three approaches, the last one has the lowest computation complexity and the best performance, the first one has a little high complexity and the worst performance, and the second one has the highest complexity for its DFT and IDFT operations. Simulation results show that one to two decibels benefits can be obtained by subspace and amplitudes tracking.
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Received: 01 November 2004
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2006, Vol. 28 
