Architecting Protocol Stack Optimizations on Mobile Devices

Applications using traditional protocol stacks (e.g. TCP/IP) from wired networks do not function efficiently in mobile wireless scenarios. This is primarily due to the layered architecture and implementation of protocol stacks. Cross layer feedback is one of the mechanisms to improve the performance of a layered stack, in mobile wireless environments. For example, transport layer retransmissions could be reduced by making it aware of network disconnections or handoff events. However, since the protocol stack is an integral part of the operating system, any such cross layer modification to the stack should not impact its efficiency, correctness and maintainability. An appropriate architecture would help ensure that cross layer modifications confirm to this requirement. In this paper, we present an architecture ECLAIR for cross layer feedback. As compared to other approaches, ECLAIR requires minimal or no modification to the stack. To evaluate the efficiency of cross layer architectures, we identify time/space complexity, design complexity, user-kernel crossing and data path delay as performance metrics. We validate and evaluate ECLAIR through a prototype implementation and experiments. Our results and analysis show that ECLAIR is efficient cross layer architecture. To enhance the efficiency of ECLAIR, we propose sub-architecture to reduce the runtime overheads. We also present a design guide for cross layer optimizations using ECLAIR