Designing energy efficient automatic repeat request protocol in wireless sensor networks
Energy constrained Wireless Sensor Networks (WSNs) challenge traditional protocols in many aspects. One such challenge is the requirement of energy eﬃciency in the Automatic Repeat Request (ARQ) protocols. Although traditional ARQ protocols are optimized for a better throughput, they fail to minimize the energy consumption. In some applications in sensor networks, delay can be tolerated. Using this aspect, we propose a link quality aware ARQ (LQ-ARQ) protocol which only retransmits packets from a buﬀer when the link from the sender to the receiver is relatively good. The link quality is judged by checking the Received Signal Strength (RSS) of the data packets, thus no extra overhead is introduced. To avoid using an inﬂexible threshold of RSS to judge a good or bad link, which is hard to decide in practise, we propose a machine learning mechanism to decide the threshold softly depending on link quality. Our protocol is able to deliver packets reliably with least amount of retransmissions. Thus energy consumption is reduced. Moreover, usage of limited resources such as memory is minimized in the protocol. We compared our protocol with traditional ARQ protocols with real ﬁeld experimental data. Results show signiﬁcant improvements.
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