Equidistance in pilot spacing is an essential condition for discrete Fourier transform (DFT)-based channel estimation in OFDM systems. However, virtual subcarriers break this condition, degrade the estimation performance, and cause the interference (called 'leakage') because the orthogonality of Fourier matrix is broken. To solve this problem, we first analyze the leakage using the DFT-inverse DFT process. The pilot subcarriers inside virtual subcarriers area are estimated by the inverse of the estimated leakage. Thus, the equidistance condition is satisfied. The proposed estimator operates well in realistic environment such as IEEE 802.16, and it is robust to an increase of virtual subcarriers.
Bibliographical noteFunding Information:
Manuscript received December 19, 2006; revised April 28, 2007 and September 6, 2007; accepted September 13, 2007. The associate editor coordinating the review of this letter and approving it for publication was A Grant. This research has been supported by the MIC (Ministry of Information and Communication), Korea, under the ITRC (Information Technology Research Center) support program supervised by the IITA (Institute of Information Technology Assessment) and by Korea Science & Engineering Foundation through the NRL Program (Grant R0A-2007-000-20043-0).
All Science Journal Classification (ASJC) codes
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics