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Optimal Pilot Placement in Cognitive Radio Systems for Wiener Filtered MMSE Channel Estimation

Authors:
Boyan Soubachov
Neco Ventura

Keywords: OFDM, cognitive radio, MMSE estimation, power loading

Abstract:
Non-contiguous Orthogonal Frequency Division Multiplexing (NC-OFDM) Cognitive Radios (CRs) pose an intriguing situation for optimal pilot-pattern generation. It has been proposed that in order to attain the lowest possible Mean Squared Error (MSE) of a channel estimator, the pilots should be placed adjacent to an interfering Primary User (PU) to allow for the highest pilot to data symbol cross-correlation and the lowest pilot auto-correlation. In past research, this has been shown to provide a significant decrease in the channel estimator’s MSE; moreover the optimal power loading required such that the PU does not experience interference above a certain threshold from the Secondary User (SU) is not taken into account. This leads to a contradiction between the optimal power loading and the optimal pilot pattern. In this paper, the relationship between these two concepts is investigated with the implementation of a Minimum Mean Squared Error (MMSE) Wiener filter and the optimal pilot positioning is derived.

Pages: 54 to 59

Copyright: Copyright (c) IARIA, 2011

Publication date: April 17, 2011

Published in: conference

ISSN: 2308-4251

ISBN: 978-1-61208-131-1

Location: Budapest, Hungary

Dates: from April 17, 2011 to April 22, 2011