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Stateless Gateways - Reducing Cellular Traffic for Event Distribution in Mobile Social Applications

The increasing capabilities of modern smartphones lead to the design of mobile social applications focusing on direct interaction between users. Ranging from mobile social networks to fully-fledged augmented reality games, these applications usually operate on contextual information to identify relevant content - most notably, the user's physical location. The resulting locality properties of the interaction between users are not well reflected by the cloud-based, centralized infrastructure utilized in today's mobile applications. Thus, data that is relevant to a group of nearby users is downloaded multiple times via the cellular network. Due to capped and/or expensive data tariffs, this can have severe impact on the user acceptance of such applications. To address this issue, we propose the concept of stateless gateways to augment cloud-based mobile social applications. A stateless gateway is chosen by the cloud to distribute information to nearby interested parties, without requiring any additional state information on the gateway itself. We integrate the concept into a location-based publish/subscribe system and show the resulting performance and cost characteristics through extensive evaluations. Our results show that the stateless concept enables frequent gateway switches, lowering the load on the cellular network by 70% for the scenario of a mobile augmented reality game. At the same time, our system achieves better fairness characteristics among participants due to a more efficient utilization of gateway nodes compared to a less flexible assignment of gateways.