Pakorn Ubolkosold

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Reliable position estimation of a Mobile Station (MS) in a GSM network is important for many applications. Because of the diverse environments including urban, rural, outdoor and indoor and the communication signals which are usually not designed for positioning, it is difficult to obtain an accurate position estimation by using only one type of(More)
Timing acquisition constitutes a major challenge in realizing highly efficient ultra-wideband (UWB) systems for applications such as indoor wireless communications. To bypass channel estimation the transmitted reference (TR) signaling is a promising candidate. In this paper, we suggest a novel data-aided timing acquisition technique for frame-level(More)
Several future space missions are being planned with large number of spacecrafts at low Earth orbit (LEO) and beyond where clock synchronization using GPS will partly be impossible or insufficient. Onboard local clock synchronization devices will be required to replace or augment the available GPS measurements to keep the clocks of the spacecrafts(More)
This paper deals with the correlation-based carrier frequency offset estimation (CFO) problem in the presence of fading-induced multiplicative noise. We derive a new closed- form estimator using the nonlinear least-squares principle in conjunction with the summation-by-parts formula. The proposed estimator, as opposed to most of the existing methods, is(More)
In this paper, the nonlinear least-squares (NLS) estimator for frequency offset in flat-fading channels is systematically derived. A simple interpolation technique is introduced to improve the estimation accuracy of the resulting NLS estimator, especially when the number of zeros padded in FFT is insufficient. Furthermore, we propose an approximated NLS(More)
Differential transmitted reference (DTR) ultra-wideband (UWB) impulse radio (IR) system is one of the most attractive solution for realizing non-coherent low data rate and low complexity UWB systems. In this paper, the bit error rate (BER) performance of DTR-UWB receivers conditioned on a channel realization is analyzed. The modeling of low complexity(More)
In this paper, we propose a constrained method to incorporate a priori flight trajectory information into the GPS derived navigation solutions which will ensure the availability and reliability of the GPS solutions even when the number of satellites reduces to less than four. Moreover, we fuse the navigation solutions derived from the proposed constrained(More)
The paper starts with a brief consideration of a novel bistatic SAR experiment and the requirements on attitude and position determination in SAR. GPS/INS integration strategies are summarized. To obtain an affordable system for the antenna pointing for footprint chasing, low-cost inertial measurement units are in the focus. By an observability analysis it(More)
The performance of the GPS based vehicle navigation will be degraded in the attenuated signal environments and reflected conditions. In this paper two types of sensor fusions are proposed to improve the reliability of GPS navigation in such environments: (1) the integration of GPS with other GNSS, including GLONASS and GALILEO, and (2) the integration of(More)
In this letter, we use the summation-by-parts formula as a simple tool to extend the estimation range of a certain class of the already existing correlation-based Doppler centroid estimators. The resulting estimators are as robust as the original ones but cover a much larger estimation range of about 50% of the pulse-repetition frequency. Two examples with(More)