Motion Planning for Optimal Information Gathering in Opportunistic Navigation Systems

Motion planning for optimal information gathering in an opportunistic navigation (OpNav) environment is considered. An OpNav environment can be thought of as a radio frequency signal landscape within which a receiver locates itself in space and time by extracting information from ambient signals of opportunity (SOPs). The receiver is assumed to draw only pseudorange-type observations from the SOPs, and such observations are fused through an estimator to produce an estimate of the receiver’s own states. Since not all SOP states in the OpNav environment may be known a priori, the receiver must estimate the unknown SOP states of interest simultaneously with its own states. In this work, the following problem is studied. A receiver with no a priori knowledge about its own states is dropped in an unknown, yet observable, OpNav environment. Assuming that the receiver can prescribe its own trajectory, what motion planning strategy should the receiver adopt in order to build a high-fidelity map of the OpNav signal landscape, while simultaneously localizing itself within this map in space and time? To answer this question, first, the minimum conditions under which the OpNav environment is fully observable are established, and the need for receiver maneuvering to achieve full observability is highlighted. Then, motivated by the fact that not all trajectories a receiver may take in the environment are equally beneficial from an information gathering point of view, a strategy for planning the motion of the receiver is proposed. The strategy is formulated in a coupled estimation and optimal control framework of a gradually identified system, where optimality is defined through various information-theoretic measures. Simulation results are presented to illustrate the improvements gained from adopting the proposed strategy over random and pre-defined receiver trajectories.Aerospace Engineering and Engineering Mechanic

The Price of Anarchy in Active Signal Landscape Map Building

Multiple receivers with a priori knowledge about their own initial states are assumed to be dropped in an unknown environment comprising multiple signals of opportunity (SOPs) transmitters. The receivers draw pseudorange observations from the SOPs. The receivers’ objective is to build a high-fidelity signal landscape map of the environment, which would enable the receivers to navigate accurately with the aid of the SOPs. The receivers could command their own maneuvers and such commands are computed so to maximize the information gathered about the SOPs in a greedy fashion. Several information fusion and decision making architectures are possible. This paper studies the price of anarchy in building signal landscape maps to assess the degradation in the map quality should the receivers produce their own maps and make their own maneuver decisions versus a completely centralized approach. In addition, a hierarchical architecture is proposed in which the receivers build their own maps and make their own decisions, but share relevant information. Such architecture is shown to produce maps of comparable quality to the completely centralized approach.Aerospace Engineering and Engineering Mechanic

Collaborative Opportunistic Navigation

Aerospace Engineering and Engineering Mechanic

A Graphical Approach to GPS Software-Defined Receiver Implementation

Global positioning system (GPS) software-defined receivers (SDRs) offer many advantages over their hardwarebased counterparts, such as flexibility, modularity, and upgradability. A typical GPS receiver is readily expressible as a block diagram, making a graphical approach a natural choice for implementing GPS SDRs. This paper presents a real-time, graphical implementation of a GPS SDR, consisting of two modes: acquisition and tracking. The acquisition mode performs a twodimensional fast Fourier transform (FFT)-based search over code offsets and Doppler frequencies. The carrier-aided code tracking mode consists of the following main building blocks: correlators, code and carrier phase detectors, code and carrier phase filters, a code generator, and a numerically-controlled oscillator. The presented GPS SDR provides an abstraction level that enables future research endeavors.Aerospace Engineering and Engineering Mechanic

Tightly-Coupled Opportunistic Navigation for Deep Urban and Indoor Positioning

A strategy is presented for exploiting the frequency stability, transmit location, and timing information of ambient radio-frequency “signals of opportunity” for the purpose of navigating in deep urban and indoor environments. The strategy, referred to as tightly-coupled opportunistic navigation (TCON), involves a receiver continually searching for signals from which to extract navigation and timing information. The receiver begins by characterizing these signals, whether downloading characterizations from a collaborative online database or performing characterizations on-the-fly. Signal observables are subsequently combined within a central estimator to produce an optimal estimate of position and time. A simple demonstration of the TCON strategy focused on timing shows that a TCONenabled receiver can characterize and use CDMA cellular signals to correct its local clock variations, allowing it to coherently integrate GNSS signals beyond 100 seconds.Aerospace Engineering and Engineering Mechanic

Adaptive Estimation of Signals of Opportunity

To exploit unknown ambient radio frequency signals of opportunity (SOPs) for positioning and navigation, one must estimate their states along with a set of parameters that characterize the stability of their oscillators. SOPs can be modeled as stochastic dynamical systems driven by process noise. The statistics of such process noise is typically unknown to the receiver wanting to exploit the SOPs for positioning and navigation. Incorrect statistical models jeopardize the estimation optimality and may cause filter divergence. This necessitates the development of adaptive filters, which provide a significant improvementover fixed filters through the filter learning process. This paper develops two such adaptive filters: an innovationbased maximum likelihood filter and an interacting multiple model filter and compares their performance and complexity. Numerical and experimental results are presented demonstrating the superiority of these filters over fixed, mismatched filters.Aerospace Engineering and Engineering Mechanic

The political determinants of the Egyptian competition law

During the 1990s, the competition law arena witnessed a huge competition laws adaptation from developing countries creating a fertile soil for scholars and practitioners of competition law to study such a phenomena. The literature mainly corresponds to the inevitable lack of enforcement of such competition legislation within developing countries. In the scholars’ attempt to address the routes of the problem, several arguments have been formed. The most important mainstream arguments focus on two different scale arguments. The first argument focuses on the pre-enactment phase that can be called “the best model”. While the second argument focuses on the post-enactment phase which concentrates its argument on analyzing the “enforcement mechanisms”. The “best model” argument provides two different points of view. The advocates of the first point of view argue that developing countries should transplant the competition law universal norms; in other words, they should transplant Western competition legislation. On the other hand, advocates of the context theory argue that developing countries should seek the contextualization approach that harness such universal/western competition law norms to the developing countries own context. Despite the fact that both “best model” and “enforcement mechanisms” seems to be theoretically different, they are related to each other in one important aspect that seems not to be recognized by the two schools’ advocates. This important fact is the role of “political determinants” of the relevant developing country. This paper focuses on the Egyptian competition law as one of the developing countries. The paper takes a different approach than mainstream literature by emphasizing the “political determinants” within the context of a developing country due to its central and important role in determining both the “best model” to be adopted in the pre-enactment phase and on the enforcement phase as well. In support of this approach, the paper magnifies the role played by “political determinants” as the third dimension that moves everything within the competition law arena, including competition policy, legislation model, and thus enforcement mechanism. The Egyptian case reflects the fact that “political determinants” should be examined more closely as it is one of the main reasons for the enforcement problems faced by developing countries

Collaborative Opportunistic Navigation

Aerospace Engineering and Engineering Mechanic

Thermodynamic Analysis of Thermoelectric Device

In this work, the thermoelectric diode is considered and electronic as well as Carnot efficiency of the device are computed. It is found that increasing emitter temperature increases the Carnot efficiency of the device; in which case, diode power intensity and electronic efficiency reduce. The second law efficiency increases with emitter to collector temperature ratio and reduces with increasing collector temperature due to increase in collector current flow

Thermodynamic Analysis of Thermoelectric Device

In this work, the thermoelectric diode is considered and electronic as well as Carnot efficiency of the device are computed. It is found that increasing emitter temperature increases the Carnot efficiency of the device; in which case, diode power intensity and electronic efficiency reduce. The second law efficiency increases with emitter to collector temperature ratio and reduces with increasing collector temperature due to increase in collector current flow