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Cooperative localization systems require some kind of communication between the different members of the network. In underwater environments this communication is not trivial, since it is based on acoustic signals that propagate in a challenging environment characterized by multipath, Doppler effect and long delays. To avoid collisions between the different members of the network, usually a Time-Division...
In underwater acoustic communications, spread-spectrum signals can be used to obtain frame synchronization in a data packet. However, the underwater channel is highly challenging due to phenomena such as multipath, Doppler effect and noise, so this detection can be difficult under certain conditions. With regards to noise, several sources can be present in the ocean at a certain time, providing a...
In communications, a spread-spectrum sequence can be used for frame synchronization in order to detect the packets arrival. This sequence is usually detected by means of a matched filter with the original code, which ideally provides a distinguishable peak among the correlation noise. The detection of this peak is crucial, since the information contained in the data packet will be lost if the peak...
Ocean noise is a complex phenomenon in underwater environments. Different processes such as shipping traffic, wind, rain or animals contribute with a different signature to the background noise, which can worsen underwater systems performance. However, in the simulation of underwater systems the common approach is to consider an additive white Gaussian noise with a certain given value. Usually, the...
Underwater acoustic channel modeling keeps being an active field of research, despite the fact that the physical effects are known since decades ago. The great variability that is found in this kind of channel makes modeling a difficult task, being highly dependent on a particular environment. For high frequencies, ray tracing is a simple and reliable solution, giving a good approximation and a lot...
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