Design and implementation of scalable distributed wireless network emulator for high-speed mobility

We designed a scalable distributed wireless network emulator for high-speed mobility. Wireless network emulators provide various conditions of mobile nodes´ dynamics and wireless links to real implementation of protocols to be evaluated based on user-defined mobility scenarios. The target of the proposed emulator is IP-based protocols for large-scale mobile wireless networks composed of a large number of high-speed vehicles. One of the biggest design issues we faced in making our network emulator effective was attaining high scalability while maintaining transparency and high accuracy. To overcome this, we first introduce a backbone-network-based distributed architecture by which we can easily add test nodes while maintaining transparency, then we introduce our new approach, which is called “time-based wireless link emulation.” In this approach, the mobility scenario is converted into a wireless link schedule, and each distributed processor emulates a wireless link based only on the schedule and its clock, which is precisely synchronized with the other processors´ clocks by using IEEE 1588 PTPv2. This approach can eliminate unnecessary overhead caused by exchange of control messages. We also introduce a distribution method of wireless link emulation in which two processors effectively share an emulation process to reduce overhead while maintaining accuracy of packet delay emulation. We briefly describe our first prototype and preliminary results of an experiment and performance evaluation.