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NC-OFDM Cognitive Radio Optimal Pilot Placement for the LS Estimator

Authors:
Boyan Soubachov
Neco Ventura

Keywords: Cognitive Radio, Power Loading, Pilot Patterns, Orthogonal Frequency Division Multiplexing

Abstract:
A theoretical contradiction between the areas of the optimal pilot-pattern design and the optimal power loading algorithms has been found to exist for proposed Non-Contiguous Orthogonal Frequency-Division Multiplexing (NC-OFDM) Cognitive Radio (CR) systems. It has been found that the proposed, optimal pilot-patterns specify that the Secondary User (SU) should convert the two sub-channels adjacent to a Primary User (PU) to pilot sub-channels in order to ensure the lowest estimator Mean Squared Error (MSE) attainable. This algorithm has been found to contradict with the optimal power loading algorithm for CR systems should the Pilot-to-Data Power Ratio (PDPR) be greater than unity. The contradiction arises in that the optimal power loading algorithms for CR systems require that, in order for interference to the PU to be kept below an acceptable threshold, the sub-channels of the SU should have less power assigned to them the closer they are to the PU. In this paper, a proof of concept is demonstrated and evaluated such that the lowest MSE possible is achieved while maintaining interference threshold constraints in a simplistic environment.

Pages: 5 to 10

Copyright: Copyright (c) IARIA, 2012

Publication date: April 29, 2012

Published in: conference

ISSN: 2308-4251

ISBN: 978-1-61208-197-7

Location: Chamonix, France

Dates: from April 29, 2012 to May 4, 2012