Elixir - Efficient Data Transfer in WiFi-based IoT Nodes

Internet-of-Things (IoT) nodes in dense WiFi deployments struggle to maintain their associations with the access points (APs) and efficiently transmit their data. In the process, they waste their energy and airtime, which affects their battery life and throughput. We present Elixir, a protocol for WiFi-based IoT nodes that enables them to transmit data without the need of a WiFi association. Elixir is implemented in the user space, which makes it easy to port the implementation to any Linux-based client and AP. We demonstrate its end-to-end operation on a Raspberry Pi module in good [signal strengths-40 to -50 dBm and no losses] and bad network conditions [signal strengths below-80 dBm and losses present]. We measure benefits of Elixir in terms of (a) the ability to transmit when the WiFi association cannot be maintained [in bad network condition], (b) lesser number of frames transmitted [50x - good network condition, 100x - bad network condition], (c) reduced airtime consumption [10x - bad network condition], and (d) reduced battery expenditure [18% for both network conditions].