Ryan A. Pacheco

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Accurate channel estimates are needed in orthogonal frequency-division multiplexing (OFDM), and easily obtained under the assumption of perfect phase and frequency synchronization. However, the practical receiver encounters nonnegligible phase noise (PHN) and carrier frequency offset (CFO), which create substantial intercarrier interference that a(More)
In this letter, the principles of Bayesian changepoint detection are applied to the problem of frame synchronization in wireless systems that use a periodic training signal as part of the packet preamble. An autocorrelation-based metric is used, which allows modeling the synchronization problem as a problem of changepoint detection of a Gaussian process. A(More)
Adhesive spider glues are required to perform a variety of tasks, including web construction, prey capture, and locomotion. To date, little is known regarding the molecular and structural features of spider glue proteins, in particular bioadhesives that interconnect dragline or scaffolding silks during three-dimensional web construction. Here we use(More)
We propose an optimal training-based OFDM channel impulse response (CIR) estimation algorithm that addresses the phase noise (PHN) and carrier frequency offset (CFO) problem. If left unattended, these combined problems severely degrade the accuracy of the channel estimate and ultimately the quality of the wireless link. The solution involves the joint(More)
QAM transmission of OFDM signals achieves good spectral efficiency while greatly simplifying the equalization process. However, RF transmitters must be operated in their linear region and highly stable oscillators (low phase-noise) are a necessity or the BER will degrade significantly. If angle-modulation is instead used, then the RF signal has constant(More)
Frame and frequency synchronization schemes are critical in the design of OFDM receivers. In burst communications, such as HIPERLAN/2 and IEEE 802.11a WLANs, synchronization must be achieved at the beginning of the packet using only the given preamble. Thus, for such systems, it's important to design accurate synchronization methods that converge quickly.(More)
We propose an efficient training-based OFDM channel impulse response (CIR) and carrier frequency offset (CFO) estimation algorithm that addresses the problem of phase noise (PHN), assuming that the PHN has a known prior distribution. The optimal joint estimation of CIR, PHN and CFO was described in an earlier work of ours. In this paper, we focus on the(More)
The aim of this survey is to investigate channel estimation method with carrier frequency offset in MIMO-OFDM systems. According to this, using maximum likelihood estimation algorithm (MLE), the carrier frequency offset (CFO) can be estimated. Then we estimate channel's coefficients for these systems. To accurately estimate the channel's(More)
As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally(More)
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