Universidad de Málaga Escuela Técnica Superior de Ingeniería de Telecomunicación Programa de Doctorado en Ingeniería de Telecomunicación TESIS DOCTORAL Cost-Effective and Energy-Efficient Techniques for Underwater Acoustic Communication Modems Autor: Muhammad Yousuf Irfan Zia Directores: Pablo Otero Roth Miguel Ángel Luque Nieto Málaga 2020 AUTOR: Muhammad Yousuf Irfan Zia https://orcid.org/0000-0003-4181-5997 EDITA: Publicaciones y Divulgación Científica. Universidad de Málaga Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial- SinObraDerivada 4.0 Internacional: http://creativecommons.org/licenses/by-nc-nd/4.0/legalcode Cualquier parte de esta obra se puede reproducir sin autorización pero con el reconocimiento y atribución de los autores. No se puede hacer uso comercial de la obra y no se puede alterar, transformar o hacer obras derivadas. Esta Tesis Doctoral está depositada en el Repositorio Institucional de la Universidad de Málaga (RIUMA): riuma.uma.es Escuela de Doctorado DECLARACIÓN DE AUTORÍA Y ORIGINALIDAD DE LA TESIS PRESENTADA PARA OBTENER EL TÍTULO DE DOCTOR D./Dña MUHAMMAD YOUSUF IRFAN ZIA Estudiante del programa de doctorado INGENIERÍA DE TELECOMUNICACIÓN de la Universidad de Málaga, autor/a de la tesis, presentada para la obtención del título de doctor por la Universidad de Málaga, titulada: COST-EFFECTIVE AND ENERGY-EFFICIENT TECHNIQUES FOR UNDERWATER ACOUSTIC COMMUNICATION MODEMS Realizada bajo la tutorización de PABLO OTERO ROTH y dirección de PABLO OTERO ROTH y MIGUEL ÁNGEL LUQUE NIETO, DECLARO QUE: La tesis presentada es una obra original que no infringe los derechos de propiedad intelectual ni los derechos de propiedad industrial u otros, conforme al ordenamiento jurídico vigente (Real Decreto Legislativo 1/1996, de 12 de abril, por el que se aprueba el texto refundido de la Ley de Propiedad Intelectual, regularizando, aclarando y armonizando las disposiciones legales vigentes sobre la materia), modificado por la Ley 2/2019, de 1 de marzo. Igualmente asumo, ante a la Universidad de Málaga y ante cualquier otra instancia, la responsabilidad que pudiera derivarse en caso de plagio de contenidos en la tesis presentada, conforme al ordenamiento jurídico vigente. En Málaga, a 26 de septiembre de 2020 Fdo.: MUHAMMAD YOUSUF IRFAN ZIA Edificio Pabellón de Gobierno. Campus El Ejido. 29071 Tel.: 952 13 10 28 / 952 13 14 61 / 952 13 71 10 E-mail: [email protected] This page intentionally left blank AUTORIZACIÓN DE LOS DIRECTORES DE TESIS DOCTORAL El alumno del Programa de Doctorado en Ingeniería de Telecomunicación, Muhammad Yousuf Irfan Zia, es primer autor de las siguientes publicaciones en revistas indexadas en los Journal Citation Reports (JCR) del Web of Science (WoS): - M.Y.I. Zia, P. Otero, J. Poncela. “Design of a low-cost modem for short-range underwater acoustic communications”. Wireless Personal Communications (Springer. ISSN: 0929- 6212), Vol. 101, No. 1, pp. 375-390, julio 2018. DOI: 10.1007/s11277-018-5694-5. - M.Y.I. Zia, P. Otero, A. Siddiqui, J. Poncela. “Design of a web based underwater acoustic communication testbed and simulation platform”. Wireless Personal Communications (Springer. ISSN: 0929-6212), 28 febrero 2020. DOI: 10.1007/s11277-020-07203-7. - M.Y.I. Zia, R. Tierno, M.Á. Luque-Nieto, P. Otero. “An energy efficient integration of a digital modulator and a class-D amplifier”. Electronics (MDPI. ISSN: 2079-9292), 16 agosto 2020. DOI: 10.3390/electronics9081319. Además, el Sr. Zia es primer autor de una publicación de revisión y estado del arte, también publicada en una revista indexada en los JCR: - M.Y.I. Zia, J. Poncela, P. Otero. “State-of-the-art underwater acoustic communication modems: classifications, analyses and design challenges”. Wireless Personal Communications (Springer. ISSN: 0929-6212), 8 mayo 2020. DOI: 10.1007/s11277-020- 07431-x. Estas publicaciones avalan su tesis doctoral y ninguna otra tesis. Por todo ello, su tutor y director de tesis Pablo Otero Roth y su codirector de tesis Miguel Ángel Luque Nieto autorizan al Sr. Zia a depositar su tesis doctoral ante las Autoridades académicas de la Universidad de Málaga. En Málaga, a 9 de septiembre de 2020. Fdo: Pablo Otero Roth Fdo: Miguel Ángel Luque Nieto This page intentionally left blank Abstract Underwater wireless sensor networks (UWSNs) are widely used in many applications related to ecosystem monitoring, search for wrecks, infrastructures maintenance, security and defense, among others. Due to the absorption of electromagnetic waves in water and line-of-sight communication of optical waves, acoustic waves are the most suitable medium of communication in underwater environments. Underwater acoustic modem (UAM) is an essential component of a UWSN which is responsible for the transmission and reception of acoustic signals in an aquatic channel. Many commercial and research modems have been designed for different applications. Commercial modems may communicate at longer distances with reliability but they are expensive and less power efficient. On the other hand, the research modems have diverse characteristics and are designed by using a digital- signal-processor (DSP) and field-programmable-gate-array (FPGA). In addition to the employment of a DSP (which is expensive) and FPGA (which is a high power consuming device), the use of a microcontroller is also a common practice (which is less expensive) but provides limited computational power. Hence, there is a need for a cost-effective and energy-efficient UAM to be used in budget limited applications. In this thesis different objectives are proposed, which have been reflected in the corresponding technical contributions. First, to identify the limitations of state-of-the-art commercial and research UAMs through a comprehensive survey. The outcome of the conducted survey is a thorough analysis/comparison in terms of various performance attributes (such as operating range, data rate, center frequency, bandwidth, bit-error-rate, power consumption etc.). Based on the outcomes of the conducted survey, the second contribution of the research has been the design of a low-cost acoustic modem for short-range underwater communications using a modular approach that can be configured for various applications. The proposed modem is based on a single board computer (Raspberry-Pi) while the low level functionality is controlled using a microcontroller (Atmega328P). Furthermore, the modulator, demodulator and amplifiers are designed with discrete components to make the design economical. Moreover, the transducers in the proposed modem are made by piezo ceramic elements to reduce the overall cost. In addition to the reduction in design cost, the verification/testing cost is equally important. In order to reduce the testing cost, the third contribution of this thesis is to design a web based underwater acoustic communication testbed along with a simulation platform. The testbed works as an emulator to test different types of modems in a controlled laboratory setup and simulates the underwater channel as well as sound propagation models. Remote accessibility of the testbed using a web browser further reduces the overall testing cost. Besides low-cost, the energy-efficiency plays an important role in difficult-to-access areas like underwater communication as these systems are operated by an electric accumulator (battery), and therefore, preserving the accumulator’s energy is of paramount importance. Power amplifier is the most energy demanding module and usually consists of a Class-D amplifier (which is the most energy efficient in terms of power). Conventionally, two different modules are used, for modulation (such as phase shift keying or frequency shift keying etc.) and amplification (such as Class-D amplifier) in an i underwater acoustics modem. Consequently, two modulations are found: once in the modulator (phase shift keying) and then in a Class-D amplifier (pulse width modulation). The fourth contribution of this thesis is based on the idea of using the side effect of phase modulation found in a PWM modulator to integrate the both the PSK modulator and the power amplifier in a single module. The final transmitter is simpler and, which is more important, shows a higher power efficiency. Furthermore, the replacement of two modules with a single module also reduces the cost of the overall system. In order to validate the proposed low-cost modem, component level as well as system level testing have been performed. For component level testing, each module such as analogue module (modulator, demodulator and amplifier), digital controller (Raspberry-Pi and microcontroller) and underwater transducers have been tested individually in a controlled laboratory setup. The individual modules are then integrated to perform system level testing in an aquatic environment at different data rates with a fixed range of 1 meter and a center frequency of 31.5 푘퐻푧. The ultrasonic frequency band is used to mitigate the issues of audible frequency range (such as noise). The data rates used for system level testing are 100, 300, 600 and 1200 bits per second (bps). The achieved results show that the proposed modem can communicate at higher data rates with better accuracy as compared to state-of-the-art research modems. To demonstrate the functionality of the proposed testbed (low-cost testing environment) as an emulator, we have used two low-cost UW acoustic modems (Modem-A and Modem-B). The electroacoustic transducers and two sensors (temperature and salinity) are submerged in an aquatic environment. Modem-A transmits the data from the sensors. The data from the sensors is received by Modem-B and transferred to a personal computer (PC) working as a LabVIEW server. Finally, the real- time data from the sensors (temperature and salinity) are monitored on a graphical user interface. The validation results show that the proposed testbed environment requires less development time, low cost and provides (local and remote) monitoring. It is important to note that the functionality of the testbed has been validated using the proposed low-cost modems. However, the proposed testbed environment can also be used to test various types of modems.