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The potential of exploiting large propagation delays in underwater acoustic (UWA) networks to maximize the network throughput is established in the recent past. Transmission scheduling strategies have been proposed to take advantage of large propagation delay. Super-TDMA is one among such Medium Access Control (MAC) strategies proposed. It is a form of Time Division Multiple Access (TDMA) protocol...
In a recent work, a regular grid-based network topology with multihop relaying was investigated. A transmission strategy which maximizes the throughput while exploiting the large propagation delay was presented, and the upper bound on throughput established. However, deployments of communication nodes in the ocean inevitably result in slight positional deviations from the expected locations of the...
Unlike terrestrial networks that mainly rely on radio waves for communications, underwater networks utilize acoustic waves, which have comparatively lower loss and longer range in underwater environments. However, acoustic waves incurs long propagation delays that typically lead to low throughput and higher energy cost of transmission than reception. Thus, collision and retransmission should be reduced...
LDPC codes are typically decoded by running a synchronous message passing algorithm over the corresponding bipartite factor graph (made of variable and check nodes). More specifically, each synchronous round consists of 1) updating all variable nodes based on the information received from the check nodes in the previous round, and then 2) updating all the check nodes based on the information sent...
Underwater acoustic communication networks face several challenges: large propagation delays, low bandwidth and high transmission power. Recent studies exploit the large propagation delay to allow concurrent transmissions in the network. Given a suitable network geometry, it has been shown that the network throughput increases linearly with the number of nodes, provided optimal transmission schedules...
Mobile underwater networking is a developing technology for monitoring and exploring the Earth's oceans. For effective underwater exploration, multimedia communications such as sonar images and low resolution videos are becoming increasingly important. Unlike terrestrial RF communication, underwater networks rely on acoustic waves as a means of communication. Unfortunately, acoustic waves incur long...
In many multi-rate periodic control systems, information flows from control modules driven at lower rates to modules driven at higher rates (i.e., from lower-priority tasks to higher-priority tasks when rate monotonic scheduling is used). If such information flow occurs in the system, unexpectedly long delays in information propagation (longer than the sum of the periods) may be observed. This could...
Underwater acoustic networks can have large propagation delays as compared to typical packet durations, as a result of the low speed of sound in water. The ill effects of large propagation delay on medium access control (MAC) are well known. Conventional MAC protocol design for such networks focuses on mitigation of the impact of propagation delay. Most proposed protocols to date achieve, at best,...
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