Performance Analysis of Adaptive Location Update Schemes for Continuous Cell Zooming Algorithm in Wireless Networks

To reduce the transmitted power of base stations in mobile wireless networks, continuous cell zooming algorithm is a feasible dynamic cell zooming algorithm. In this algorithm, location management is required in order to know the locations of users. Movement-based Update is not compatible and the application of Convention Periodic Update (CPU) scheme in continuous cell zooming algorithm can lead to a high signaling cost. Thus, aiming to highlight the effectiveness of newly proposed location update schemes, Time-Adaptive Periodic Update (TAPU) and Location-Adaptive Periodic Update (LAPU), a simulation-based performance analysis is conducted. Applying in continuous cell zooming algorithm, the performances of TAPU and LAPU are compared to that of Convention Periodic Update (CPU) scheme in terms of transmitted power ratio, outage ratio and the number of update messages. The performances of TAPU and LAPU are analyzed in a network with different number of users and in a network with different average moving speeds of users. The results show that compared to CPU, both TAPU and LAPU have no significant effect on power saving capability of continuous cell zooming algorithm in every scenario. Meanwhile, LAPU and TAPU give a significant reduction of update messages in every scenario. In terms of QoS effect, LAPU gives approximately the same outage ratio as CPU and a higher outage ratio occurs in TAPU

Analysis of User Mobility Models Based on Outdoor Measurement Data and Literature Surveys

The main objectives of the presented work are to study the various existing human mobility models based on literature reviews and to select an appropriate and simplified mobility model fit to the available measurement data. This thesis work is mainly processing a part of “Big Data” that was collected from large number of people, known as Mobile Data Challenge (MDC). MDC is large scale data collection from Smartphone based research. The thesis also addressed the fact that appropriate mobility models could be utilized in many important practical applications, such as in public health care units, for elderly care and monitoring, to improve the localization algorithms, in cellular communications networks to avoid traffic congestion, for designing of such systems that can predict prior users location, in economic forecasting, for public transportation systems and for developing social mobile applications. Basically, mobility models indicate the movement patterns of users and how their position, velocity and acceleration vary with respect to time. Such models can be widely used in the investigation of advanced communication and navigation techniques. These human mobility models are normally classified into two main models, namely; entity mobility models and group mobility models. The presented work focuses on the entity mobility models. The analysis was done in Matlab, based on the measurement data available in MDC database, the several parameters of Global Positioning System (GPS) data were extracted, such as time, latitude, longitude, altitude, speed, horizontal accuracy, horizontal Dilution of Precision (DOP), vertical accuracy, vertical DOP, speed accuracy etc. Parts of these parameters, namely the time, latitude, longitude, altitude and speed were further investigated in the context of basic random walk mobility model. The data extracted from the measurements was compared with the 2-D random walk mobility model. The main findings of the thesis are that the random walk model is not a perfect fit for the available user measurement data, but can be used as a starting point in analyzing the user mobility models

Groundwater Contamination and Remediation

This Special Issue of Water brings together 10 studies on groundwater contamination and remediation. Common themes include practical techniques for plume identification and delineation, the central role of subsurface processes, the pervasiveness of non-Fickian transport, and the importance of bacterial communities in the broader context of biogeochemistry

Modeling Human Mobility Entropy as a Function of Spatial and Temporal Quantizations

The knowledge of human mobility is an integral component of several different branches of research and planning, including delay tolerant network routing, cellular network planning, disease prevention, and urban planning. The uncertainty associated with a person's movement plays a central role in movement predictability studies. The uncertainty can be quantified in a succinct manner using entropy rate, which is based on the information theoretic entropy. The entropy rate is usually calculated from past mobility traces. While the uncertainty, and therefore, the entropy rate depend on the human behavior, the entropy rate is not invariant to spatial resolution and sampling interval employed to collect mobility traces. The entropy rate of a person is a manifestation of the observable features in the person's mobility traces. Like entropy rate, these features are also dependent on spatio-temporal quantization. Different mobility studies are carried out using different spatio-temporal quantization, which can obscure the behavioral differences of the study populations. But these behavioral differences are important for population-specific planning. The goal of dissertation is to develop a theoretical model that will address this shortcoming of mobility studies by separating parameters pertaining to human behavior from the spatial and temporal parameters