Coast: Collaborative Application-Aware Scheduling Of Last-Mile Cellular Traffic

The explosive growth of mobile data traffic poses severe pressure on cellular providers to better manage their finite spectrum. Proposed solutions such as congestion-pricing exist, but they degrade users' ability to use the network when they want. In this paper, we propose a fundamentally different approach - rather than reducing the aggregate busy hour traffic, we seek to smooth the peaks that cause congestion. Our approach is based on two key insights obtained from traffic traces of a large cellular provider. First, mobile traffic demonstrates high short-term variation so that delaying traffic for very short periods of time can significantly reduce peaks. Second, by making collaborative decisions on which traffic gets delayed and by how much across all users of a cell, the delays need not result in any degradation of user experience. We design a system, CoAST, to implement this approach using three key mechanisms: a protocol to allow mobile applications and providers to exchange traffic information, an incentive mechanism to incentivize mobile applications to collaboratively delay traffic at the right time, and mechanisms to delay application traffic. We provide extensive evaluations that show that CoAST reduces traffic peaks by up to 50% even for applications that are not thought to be delay-tolerant, e.g., streaming and web browsing, but which together account for 70% of all cellular traffic.