Underwater is a harsh and dynamic environ-
ment. Its physical properties are unsteady in the space-time
domain and that complicates the communication process
inside the water. Moreover, underwater transmissions suffer
from many attenuations and scattering sources due to several
environmental noises such as shipping, turbulence, wave
dynamics, and the background life of the marine organisms.
Therefore, opportunistic and cooperative communications
are necessary to compensate for the prompt changes in
underwater environments. In this paper, we propose a new
opportunistic cooperative transmission scheme for under-
water networks that is adaptable for various environmental
conditions. The proposed scheme employs the key physical
variables of the seawater, e.g. temperature, salinity, density, and waves speed, to indicate the proper relaying scheme
jointly with the appropriate modulation method and the transmitting power level that suit the current transmission
situations. The paper also proposes a study that demonstrates the effects of these variables on the underwater speed
of sound which is the most commonly used carrier for underwater communication and hence affects the transmitted
signal intensity. The results show that the proposed opportunistic cooperative transmission scheme provides an efficient
compromise between the overall network performance and the energy efficiency at the nodes. |
