Browsing by Subject "Ultra-wideband (UWB) cognitive radio"

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    Theoretical limits on time delay estimation for ultra-wideband cognitive radios
    (IEEE, 2008-09) Gezici, Sinan; Celebi, H.; Arslan, H.; Poor, H. V.
    In this paper, theoretical limits on time delay estimation are studied for ultra-wideband (UWB) cognitive radio systems. For a generic UWB spectrum with dispersed bands, the Cramer-Rao lower bound (CRLB) is derived for unknown channel coefficients and carrier-frequency offsets (CFOs). Then, the effects of unknown channel coefficients and CFOs are investigated for linearly and non-linearly modulated training signals by obtaining specific CRLB expressions. It is shown that for linear modulations with a constant envelope, the effects of the unknown parameters can be mitigated. Finally, numerical results, which support the theoretical analysis, are presented. © 2008 IEEE.