WiZi-Cloud: Application-transparent dual ZigBee-WiFi radios for low power internet access

The high density ofWiFi Access Points and large unlicensed RF bandwidth over which they operate makes them good candidates to alleviate cellular network's limitations. However, maintaining connectivity through WiFi results in depleting the mobile phone's battery in a very short time. We propose WiZi-Cloud, a system that utilizes a dual WiFi-ZigBee radio on mobile phones and Access Points, supported by WiZi-Cloud protocols, to achieve ubiquitous connectivity, high energy efficiency, real time intra-device/inter-AP handover, that is transparent to the applications. WiZi-Cloud runs mostly on commodity hardware such as Android phones and OpenWrt capable access points. Our extensive set of experiments demonstrate that for maintaining connectivity, WiZi-Cloud achieves more than a factor of 11 improvement in energy consumption in comparison with energy-optimized WiFi, and a factor of 7 in comparison with GSM. WiZi-Cloud has a better coverage than WiFi, and a low delay resulting in a good Mean Opinion Score (MOS) of 4.26 for a VoIP US cross-country communication.