CA-Fi: Ubiquitous mobile wireless networking without 802.11 overhead and restrictions

The proliferation, flexibility, and mobility of wireless communication devices provides a readily available basis for ubiquitous mobile communication. However, the network-centric design of 802.11 does not support the spontaneity, continuity, and ubiquitous scope of mobile communication for two reasons: i) The time and maintenance overhead of 802.11 networks prevents spontaneous device interaction, and ii) 802.11 restricts the communication scope to devices in a common network. We thus enable ubiquitous wireless communication, independent from 802.11 network structures in CA-Fi, a continuous, low-overhead communication channel concurrent to 802.11 associations. CA-Fi augments 802.11 with an association-less broadcast mechanism of up to 30 kB/s, preserving up to 70 % of simultaneous 802.11 throughput and enabling unrestricted and instant networking in the wireless medium. Directly addressing applications in 802.11 frames using Bloom filters enables message aggregation for space efficiency and saves communication overhead by unifying peer and application discovery. CA-Fi inherently supports duty cycling and saves up to 44 % of the energy consumption of the 802.11 ad-hoc mode.