Abstract

The performance gap between mobile phones and computers shrinks with advancing mobile phone technology. Powerful mobile devices with fast networking can easily participate in an overlay network like a Distributed Hash Table. But NAT traversal remains a challenge of P2P systems because peers need to be able to interact with each other. Another challenge is the limited power capacity of mobile devices. Networking is one of the most battery-draining component of mobile phones, but essential for the participation in a P2P network. This thesis proposes multiple NAT traversal techniques using relay peers and long-living TCP connections between the relays and the mobile phones. To reduce the battery consumption, buffered relaying techniques are presented that allow the mobile phone to longer remain in the sleep mode. Another optimization is the replacement of the long-living TCP connection with the mobile operating system’s push notification service. The evaluation confirms a reduction of the energy consumption when using the optimized buffered push notification relaying technique. While only 6% of energy can be saved in Wifi, up to 30% less battery is consumed in a 3G cellular network. These insights are used for the implementation of a distributed file synchronization client on Android.