Throughput Analysis on Slotted Underwater Acoustic Sensor Networks With Guard Time

A guard time is a short time interval that is added between packet transmissions, and has been applied in time- slotted underwater acoustic sensor networks (UASNs) to balance the transmission rate and the inter-slot interference. In this article, we take a physical-layer approach and investigate the throughput performance in time-slotted UASN with guard time. Based on the geographical node distribution, we first derive the probability distribution of the arrival time of an interfering packet and further the distribution of the packet overlap duration. We then derive the expression of the probability density functions (pdfs) of the signal-to-interference-plus-noise ratio (SINR). Expressions for the outage probability and the normalized throughput of a typical link between two nodes are also obtained. We show that when the length of guard time is properly selected, time-slotted network with guard time has higher throughput than those without guard time. Simulation results validate the theoretical results and illustrate typical features of the interference in an underwater network.

Automated summary

In this article, the throughput performance of time-slotted underwater acoustic sensor networks (UASNs) with guard time is investigated. The probability distributions of the arrival time of interfering packets and the packet overlap duration are derived based on the geographical node distribution. The expressions of the probability density functions (pdfs) of the signal-to-interference-plus-noise ratio (SINR), as well as the outage probability and normalized throughput for a typical link between two nodes, are obtained. The results show that properly selected guard time length can increase the throughput of time-slotted networks compared to those without guard time. Simulation results validate the theoretical findings and illustrate the interference characteristics in underwater networks.