Energy Consumption of Always-On Applications in WCDMA Networks

Always-on applications, such as push email and voice-over-IP, are characterized by the need to be constantly reachable for incoming communications. In the presence of stateful firewalls or NATs, such applications require "keep-alive" messages to maintain up-to-date connection state in the firewall or NAT, and thus preserve reachability. In this paper, we analyze how these keep-alive messages influence battery lifetime in WCDMA networks. Using measurements in a 3G network, we show that the energy consumption is significantly influenced by the radio resource control (RRC) parameters and the frequency of keep-alive messages. The results suggest that especially UDP-based protocols, such as mobile IPv4 and IPsec NAT traversal mechanisms, require very frequent keep-alives that can lead to unacceptably short battery lifetimes.