134 research outputs found
Range estimation in multicarrier systems in the presence of interference: Performance limits and optimal signal design
Cataloged from PDF version of article.Theoretical limits on time-of-arrival (equivalently, range) estimation are derived for multicarrier systems in the presence of interference. Specifically, closed-form expressions are obtained for Cramer-Rao bounds (CRBs) in various scenarios. In addition, based on CRB expressions, an optimal power allocation (or, spectrum shaping) strategy is proposed. This strategy considers the constraints not only from the sensed interference level but also from the regulatory emission mask. Numerical results are presented to illustrate the improvements achievable with the optimal power allocation scheme, and a maximum likelihood time-of-arrival estimation algorithm is studied to assess the effects of the proposed approach in practical estimators. © 2011 IEEE
Performance limits on ranging with cognitive radio
Cognitive radio is a promising paradigm for efficient utilization of the radio spectrum due to its capability to sense environmental conditions and adapt its communication and localization features. In this paper, the theoretical limits on time-of-arrival estimation for cognitive radio localization systems are derived in the presence of interference. In addition, an optimal spectrum allocation strategy which provides the best ranging accuracy limits is proposed. The strategy accounts for the constraints from the sensed interference level as well as from the regulatory emission mask. Numerical results are presented to illustrate the improvements that can be achieved by the proposed approach. © 2009 IEEE
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STATISTICAL DYNAMICS OF A FIRST-ORDER PHASE-LOCKED LOOP
International Telemetering Conference Proceedings / October 10-12, 1972 / International Hotel, Los Angeles, CaliforniaThe paper deals with a procedure for studying the transient behavior of a first-order phase-locked loop in the presence of noise. This procedure requires the numerical solution of an ordinary differential equation. Excellent agreement has been found between theoretical results and those obtained via computer simulation.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection
Joint Frequency and Timing Recovery for MSK-Type Modulation
We investigate a novel nondata-aided method for jointly estimating timing and carrier frequency offset in MSK-type modulation. The algorithm has a feedforward structure and lends itself to a simple digital implementation. Its estimation accuracy depends on a design parameter that may be varied to trade performance for computational complexity. Setting the parameter to unity yields a synchronization scheme already known in the literature. Computer simulations are used to assess the synchronizer performance on AWGN Rayleigh fading channels with MSK and Gaussian MSK modulation
Carrier-Frequency Estimation for Transmissions over Selective Channels
This paper deals with carrier-frequency estimation
for burst transmissions over frequency-selective channels. Three
estimation schemes are proposed, all based on the use of known
training sequences. The first scheme employs an arbitrary sequence
and provides joint maximum-likelihood (ML) estimates
of the carrier frequency and the channel response. Its implementation
complexity is relatively high but its accuracy achieves
the Cramer–Rao bound. The second scheme is still based on
the ML criterion, but the training sequence is periodic, which
helps to reduce the computational load. The third scheme also
employs periodic sequences, but its structure comes from heuristic
reasoning. Theoretical analysis and simulations are employed to
assess the performance of the three schemes
Code-multiplexed UWB Transmitted-Reference Radio
In traditional transmitted reference (TR) ultrawideband
systems the reference component is time-shifted and
orthogonal relative to the data-bearing signal. This paves the
way to a correlation receiver in which the local template is
derived from the incoming waveform using a delay line. As analog
delay lines are difficult to implement with current technology,
an alternative TR system has recently been proposed in which
reference and data components are made orthogonal by a
frequency shift rather than a time shift. The resulting receiver
has no delay lines and has better performance compared to
the traditional scheme. In the present paper we discuss a third
way to achieve orthogonality, i.e., by modulating reference and
data components with two distinct code sequences. Even in this
case the receiver has no delay lines. However, it is simpler to
implement and has better performance than the frequency-shift
based receiver
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