A study on unpredictable shallow water channel behavior by various multipath patterns and experimental data analysis

In shallow water applications, multipath signal propagation is a major concern for robust communication. Multipath signal propagation is not explicitly seen in the channel, even though it is a main contributor for signal degradation. This fact motivated us to simulate multipath patterns to understand its influence in short-range communication. In this paper, a three-path signal propagation model is presented, where, besides the line of sight (LOS) signal, other two non-line of sight (NLOS) signals contact any point of channel boundary to reach the receiver. In simulation, the combination of eight possible multipath patterns is converged to estimate the received signal. A source fixed in water-tank periodically transmits low frequency acoustic signals 1 kHz and 1.5 kHz to the channel, and the receiver records them. The experiment was repeated for various input signal strengths. It has been observed that the simulation results coincide with the measured values. The good reception is noticed for signal frequency 1 kHz at 2.5m and 1.5 kHz at 1.2m. This study identifies the optimal signal strength for better signal reception in short range, which drives to the establishment of high-quality communication in shallow water.

INTERFERENCE RESISTANCE OF THE MCWILL SYSTEM

Рассмотрены проблемы помехоустойчивости алгоритмов цифровой обработки принимаемых сигналов для системы связи МАКВИЛ. Особое внимание уделено вопросам коррекции амплитудно-частотных и фазо-частотных искажений радиоканала в условиях предельно низких отношений сигнал/шум. Произведена оценка потенциальных возможностей улучшения показателя чувствительности при многолучевом распространении сигналов. Выявлены наилучшие алгоритмы. Показано, что для диапазона частот 340 МГц абоненты системы МАКВИЛ, перемещающиеся со скоростями до 6 м/с, при рассмотрении вопроса помехоустойчивости могут восприниматься как стационарные. Problems of interference resistance of algorithms of digital processing of received signals for the McWiLL communication system are considered. Particular attention is paid to the correction of the amplitude-frequency and phase-frequency distortions of the radio channel in conditions of extremely low signal-to-noise ratios. The potential for improving the sensitivity index for multipath signal propagation is assessed. The best algorithms are identified. It is established that for the frequency range of 340 MHz McWiLL system subscribers moving at speeds up to 6 m/s can be perceived as stationary when considering the interference resistance issues.

Indoor Positioning System Based on Fuzzy Logic and WLAN Infrastructure

This paper deals with the issue of mobile device localization in the environment of buildings, which is suitable for use in healthcare or crisis management. The developed localization system is based on wireless Local Area Network (LAN) infrastructure (commonly referred to as Wi-Fi), evaluating signal strength from different access points, using the fingerprinting method for localization. The most serious problems consist in multipath signal propagation and the different sensitivities (calibration) of Wi-Fi adapters installed in different mobile devices. To solve these issues, an algorithm based on fuzzy logic is proposed to optimize the localization performance. The localization system consists of five elements, which are mobile applications for Android OS, a fuzzy derivation model, and a web surveillance environment for displaying the localization results. All of these elements use a database and shared storage on a virtualized server running Ubuntu. The developed system is implemented in Java for Android-based mobile devices and successfully tested. The average accuracy is satisfactory for determining the position of a client device on the level of rooms.

Investigation of Deterministic, Statistical and Parametric NB-PLC Channel Modeling Techniques for Advanced Metering Infrastructure

This paper is focused on the channel modeling techniques for implementation of narrowband power line communication (NB-PLC) over medium voltage (MV) network for the purpose of advanced metering infrastructure (AMI). Three different types of models, based on deterministic method, statistical method, and network parameters based method are investigated in detail. Transmission line (TL) theory model is used to express the MV network as a two-port network to examine characteristics of sending and receiving NB-PLC signals. Multipath signal propagation model is used to incorporate the effect of multipath signals to determine the NB-PLC transfer function. A Simulink model is proposed which considers the values of MV network to examine the characteristics of NB-PLC signals. Frequency selectivity is also introduced in the impedances to compare variations and characteristics with constant impedances based MV network. A state-of-the-art mechanism for the modeling of capacitive coupling device, and impedances of low voltage (LV) and MV networks is developed. Moreover, a comparative analysis of TL theory and multipath signal propagation models with the proposed Simulink model is presented to validate the performance and accuracy of proposed model. This research work will pave the way to improve the efficiency of next-generation NB-PLC technologies.