title: Underwater Communications for Video Surveillance Systems at 2.4 GHz.
abstract: Video surveillance is needed to control many activities performed in underwater environments. The use of wired media can be a problem since the material specially designed for underwater environments is very expensive. In order to transmit the images and videos wirelessly under water, three main technologies can be used: acoustic waves, which do not provide high bandwidth, optical signals, although the effect of light dispersion in water severely penalizes the transmitted signals and therefore, despite offering high transfer rates, the maximum distance is very small, and electromagnetic (EM) waves, which can provide enough bandwidth for video delivery. In the cases where the distance between transmitter and receiver is short, the use of EM waves would be an interesting option since they provide high enough data transfer rates to transmit videos with high resolution. This paper presents a practical study of the behavior of EM waves at 2.4 GHz in freshwater underwater environments. First, we discuss the minimum requirements of a network to allow video delivery. From these results, we measure the maximum distance between nodes and the round trip time (RTT) value depending on several parameters such as data transfer rate, signal modulations, working frequency, and water temperature. The results are statistically analyzed to determine their relation. Finally, the EM waves' behavior is modeled by a set of equations. The results show that there are some combinations of working frequency, modulation, transfer rate and temperature that offer better results than others. Our work shows that short communication distances with high data transfer rates is feasible.
authors: Signal Theory, Telematics and Communications Department (TSTC), Universidad de Granada, C/Periodista Daniel Saucedo Aranda, s/n., Granada 18071, Spain. ssendra@ugr.es.|Integrated Management Coastal Research Institute, Universidad Politécnica de Valencia, C/Paranimf, n° 1, Grao de Gandia 46730, Spain. ssendra@ugr.es.
authors: Sandra
authors: S
authors: Sendra
authors: Integrated Management Coastal Research Institute, Universidad Politécnica de Valencia, C/Paranimf, n° 1, Grao de Gandia 46730, Spain. jlloret@dcom.upv.es.
authors: Jaime
authors: J
authors: Lloret
authors: Integrated Management Coastal Research Institute, Universidad Politécnica de Valencia, C/Paranimf, n° 1, Grao de Gandia 46730, Spain. jojiher@dcom.upv.es.
authors: Jose Miguel
authors: JM
authors: Jimenez
authors: National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí 37540-000, Brazil. joeljr@ieee.org.|Instituto de Telecomunicações, Universidade da Beira Interior, Rua Marquês d'Ávila e Bolama, Covilhã 6201-001, Portugal. joeljr@ieee.org.|ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia. joeljr@ieee.org.
authors: Joel J P C
authors: JJ
authors: Rodrigues
keywords: 2.4 GHz; electromagnetic waves; freshwater; modulations; underwater communications; underwater video surveillance; underwater wireless sensor network (UWSN); video transmission