PCRA - um protocolo cooperativo de acesso ao meio para redes de sensores aquáticas

Abstract

Monitoring underwater environments is still a hard and costly task. Indeed, electromagnetic and optical waves suffer high attenuation, being absorbed in a few meters and even acoustic communication presents low throughput and high bit error rate. Most of the existing approaches to enhance underwater communication performance relies on developing acoustic modems, multiple access of the communication channel, and data routing. In this paper we present PCRA: a Cooperative Protocol for Underwater Sensor Networks. PCRA synchronously/asynchronously works on top of TDMA method combined with an ARQ scheme based on selective repeat technique. Each node that has no data to transmit can become a cooperator and retransmit messages to assist neighboring nodes. It uses idle sensor nodes as relay nodes, enhancing communication space diversity. Our simulations show that, when compared to a non-cooperative protocol, PCRA enhances overall network performance metrics. For instance, it reduces packet error rate by 65% and increases goodput by 16% while spending less than 1% more energy.