We propose a new channel estimation technique to mitigate interference with the aid of pilot density discrepancy in a cellular OFDM system, especially for 3GPP systems. The proposed estimator applies interference mitigation to pilot symbols, using repeated interference features according to the pilot subcarrier distance. In order to use this property, the proposed estimator employs a specific pilot structure which consists of two types of pilot symbols with different pilot density. The combination of interference alleviation and pilot rearrangement not only makes the channel estimation robust to the time-selectivity of the channel but also reduces the number of pilot subcarriers needed to estimate the channel. To clarify the advantages of the proposed method, the average mean square errors (MSE) of the frequency channel estimate are derived for the proposed estimator with unequal pilot density, and it is compared with general estimators with equal pilot density. Numerical analysis and simulation results confirm that the proposed estimator with unequal density relationship outperforms the estimators over practical time-varying environments in terms of MSE performance and pilot overhead efficiency.
Bibliographical noteFunding Information:
Manuscript received January 30, 2007; revised September 6 and December 20, 2007; accepted December 21, 2007. The associate editor coordinating the review of this letter and approving it for publication was A. Swami. This work is supported in part 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 in part 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