An introduction to signal detection and estimation (2nd ed.)
An introduction to signal detection and estimation (2nd ed.)
Wireless Communications
Cognitive Radio, Software Defined Radio, and Adaptive Wireless Systems (Signals and Communication Technology)
Analysis and design of cognitive radio networks and distributed radio resource management algorithms
Analysis and design of cognitive radio networks and distributed radio resource management algorithms
A Survey on Wireless Position Estimation
Wireless Personal Communications: An International Journal
Enabling location and environment awareness in cognitive radios
Computer Communications
Fundamental limits on time delay estimation in dispersed spectrum cognitive radio systems
IEEE Transactions on Wireless Communications
Ultra-wideband Positioning Systems: Theoretical Limits, Ranging Algorithms, and Protocols
Ultra-wideband Positioning Systems: Theoretical Limits, Ranging Algorithms, and Protocols
Utilization of Location Information in Cognitive Wireless Networks
IEEE Wireless Communications
IEEE Transactions on Wireless Communications
Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency
IEEE Communications Magazine
Exploiting location awareness toward improved wireless system design in cognitive radio
IEEE Communications Magazine
Cognitive radio: brain-empowered wireless communications
IEEE Journal on Selected Areas in Communications
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Time-delay estimation is studied for cognitive radio systems, which facilitate opportunistic use of spectral resources. A two-step approach is proposed to obtain accurate time-delay estimates of signals that occupy multiple dispersed bands simultaneously, with significantly lower computational complexity than the optimal maximum likelihood (ML) estimator. In the first step of the proposed approach, an ML estimator is used for each band of the signal in order to estimate the unknown parameters of the signal occupying that band. Then, in the second step, the estimates from the first step are combined in various ways in order to obtain the final time-delay estimate. The combining techniques that are used in the second step are called optimal combining, signal-to-noise ratio (SNR) combining, selection combining, and equal combining. It is shown that the performance of the optimal combining technique gets very close to the Cramer-Rao lower bound at high SNRs. These combining techniques provide various mechanisms for diversity combining for time-delay estimation and extend the concept of diversity in communications systems to the time-delay estimation problem in cognitive radio systems. Simulation results are presented to evaluate the performance of the proposed estimators and to verify the theoretical analysis.