IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Regular Section
Joint Estimation of Channel and Control Signal Using Noise Subspace in OFDM Systems
Bin SHENGPengcheng ZHUXin FANGWanlin LI
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2014 Volume E97.B Issue 11 Pages 2404-2412

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Abstract

Accurate channel estimation is necessary before we can demodulate orthogonal frequency division multiplexing (OFDM) signals since the radio channel is frequency-selective and time-varying for wideband mobile communication systems. For pilot-symbol-aided channel estimation, pilot sequences are inserted periodically into the data stream enabling coherent detection at receiver. The control signal information can be embedded in pilot sequences and transmitted implicitly in OFDM systems to save the bandwidth. In order to estimate the channel and control signal jointly at the receiver, we propose a novel noise subspace based method in this paper. The proposed method is developed from the DFT-based channel estimator. If the hypothesized sequence coincides with the transmitted pilot sequence, the last part of the channel impulse response (CIR) estimate is only contributed by Gaussian noise and its average power is expected to be the minimum among all possible hypothesized sequences. Simulation results show that the proposed method works well in any of the channels even if integer carrier frequency offset (CFO) is considered.

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© 2014 The Institute of Electronics, Information and Communication Engineers
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