An Asynchronous Anycast Cross-layer Protocol for WSN Suited to Noisy Environments

Abstract

This paper presents AGA-MAC+: an asynchronous anycast protocol for wireless sensor networks. Latency is a problem for asynchronous MAC due to sleep-delay, since each relay must wait for the receiver to wake-up. Our protocol employs anycast communication to mitigate the one-hop-delay, selecting a group of neighboring nodes (Forwarding Candidate Set—FCS) as possible next hop. The first FCS member to wake up becomes the next relay, reducing latency. This new protocol is an improvement over AGA-MAC, our previous work, which considers data size to determine the number of FCS members. For large packets, small FCS leads to lower latency, whereas the reverse is true for small packets. This work expands this model, considering the quality of communication channels in FCS selection. In order to receive an error-free data packet with a given probability, nodes with a minimum signal-to-interference-plus-noise ratio (SINR) can take part in FCS. The performance of our protocol was evaluated using GrubiX Simulator, considering an environment with noise and interference. AGA-MAC+ was compared with two other well-known protocols, for different packet sizes and SINR values. Comparing energy spent in the communication process, AGA-MAC+ presented a performance gain of at least 5%, in 88% of the cases. When latency is assessed, AGA-MAC+ outperforms both protocols for all scenarios, presenting an improvement of at least 18% in 83% of the tests.