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Algorithms and Bounds for Distributed TDOA-Based Positioning Using OFDM Signals

One main drawback of using time difference of arrival (TDOA) methods for source localization and navigation is that they require centralization of multiple copies of a signal. This paper considers blindly estimating the location of a cyclic prefix (CP) in an orthogonal frequency division multiplexing (OFDM) signal, enabling distributed TDOA computation up to an integer ambiguity. This ambiguity can be resolved using integer least-squares methods, if enough TDOAs are available, requiring only minimal cooperation between receivers. The contributions of this paper are development of an algorithm for simultaneously resolving the integer ambiguities and obtaining a position estimate; and derivation of the Cramér-Rao lower bound (CRLB) on locating the CP, and hence, on the underlying source localization and navigation problems.