Abstract: Packet loss is observed to be a familiar phenomenon with transmissions of wireless sensor networks (WSNs). Frequent undesired packet loss seriously degrades the network performance. Since the causes of packet loss include a variety of factors, the existing designs to resolve the packet loss problem appear to be either complicated or inefficient. The realworld observations in GreenOrbs, a longterm largescale WSN system in the forest, reveal that RSSI (Received Signal Strength Indication) is a significant indicator of packet loss. Packets with RSSI near the noise floor (called gray region in this paper) suffer remarkable loss at the receiving node. Based on such observations, we propose a lightweight selfadaptive approach called SAR2 to mitigate packet loss, which include transmission rate regulation, transmission power regulation, and dynamic parent switch, respectively. We have implemented SAR2 on the TelosB motes. The experimental results demonstrate that SAR2 mitigates packet loss and enhances the network throughput.

Key words: wireless sensor network, packet loss, RSSI