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.