China
Africa
Explore chapters and articles related to this topic
The Future
Published in Indrakshi Dey, Propagation Modeling for Wireless Communications, 2022
We can start by formulating the fundamental two-way wave equations and solving them for different environments by using different techniques. The two-way wave equations can be used to characterize the interaction between the fundamental propagating field (wave) and its time-delayed and attenuated copies reflected by obstacles in the environment, when electromagnetic and acoustic waves are used for carrying information. The two-way wave equation can describe both electromagnetic and mechanical wave propagation in any complex medium. However, the way they are solved depends on the medium under consideration. For example, for underwater acoustic communication, discretization of variable-density acoustic wave equation to quantify the filed strength. For quantum-based communication, analogy between paraxial wave equation and stationary Schrodinger equation can be used to characterize the travelling quantum field. For molecular diffusion-based communication, analogy between one-way wave equation and one-way diffusion, advective diffusion and turbulent advective diffusion equations can be used to calculate the propagating diffusion field.
Routing Protocols in Opportunistic Networks – A Survey
Published in IETE Technical Review, 2018
Majeed Alajeely, Robin Doss, Asma'a Ahmad
Underwater acoustic communication is the communication in the water using acoustic signals. In water, the attenuation of radio waves rises proportionally with conductivity of the water and signal frequency. In water, the radio waves do not spread effectively due to attenuation other than low-frequency signals that travels up to a very short distance [14]. Therefore, the communication in underwater is achieved using acoustic signals for a frequency range between 10 Hz and 1 MHz. The underwater acoustic communication is characterized by low propagation speed of the sound waves inside water (such as 1500 m/s), variable propagation delay, and Doppler shift.
A review on the internet of thing (IoT) technologies in controlling ocean environment
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Dinh Tung Vo, Xuan Phuong Nguyen, Thai Duong Nguyen, Rahmat Hidayat, Thanh Tung Huynh, Dinh Tuyen Nguyen
A radio module is necessary for a sensor node to wirelessly communicate. Access distance from the device in the backbone network to the user’s terminal is from 100 m to 10 km. Wireless communication networks in IoT-based ocean environment controlling and protection systems may require different specifications, which include reliability and energy efficiency. As to reliability, vulnerabilities of radio signals can be caused by radio antenna instability and a severe ocean environment. Regarding energy efficiency, a low level of power consumption plays a crucial role in supporting long-flow and keeping the cost for maintenance marginal in stand-alone battery-powered gadgets (Olszewski and Ghaemi 2018; Pan 2018). This factor is especially essential when devices are deployed in remote areas which causes difficulties in the upkeeping process. There have been considerable developments in wireless communication technologies regarding the current requirements. A myriad of wireless communication standards has been put forward and advanced, such as Wi-Fi, ZigBee, Bluetooth, GPRS, GSM, and WiMAX. The previous survey has illustrated a brief comparison of these wireless technologies (Xu, Shen, and Wang 2014). Generally, more than one wireless communication technology is deployed in an ocean environment management and monitoring system with integrated IoT technologies. For example, in some applications, underwater acoustic communication technology is implemented to collect data and communicate with underwater sensors (Sivakumar 2020). A communication that has a longer range typically records a higher consumption of energy. Factors that influence the selection of wireless communication technology include the volume of data, frequency and location, and type of energy supplied (Pham, Hoang, and Do 2020).