Exploiting the short message service as a control channel in challenged network environments

The Short Message Service (SMS) is one of the most ubiquitous wireless technologies on Earth. Each year hundreds of billions of messages are sent, demand continues to grow, and competition between cellular providers is driving prices down. These trends create practical opportunities for SMS in today's mobile systems. In this paper we present the design and implementation of a robust SMS-based data channel, or SMS-NIC, that runs on a variety of mobile platforms. Through integration with an existing mobile system, we show that the SMS-NIC has little operational overhead and provides efficient, reliable transport for large messages send over the cellular network. We motivate the design of the SMS-NIC through a characterization of SMS using workloads consisting of bursts of messages between cell phones tethered to Linux PCs and between smartphones. This analysis differs from previous SMS studies by focusing on transmission patterns that differ from normal SMS use. Through this characterization we show that bidirectional traffic and the choice of hardware have a significant effect on transmission rate, delay, and message reordering. We also show that burst size has no effect on SMS, losses are rare, and messages may be duplicated during transport.