Synchronous distributed wireless network emulator for high-speed mobility: Implementation and evaluation

Wireless network emulators provide various mobile node dynamic conditions and wireless links for real implementation of protocols to be evaluated based on user-defined mobility scenarios. The target of our proposed emulator is IP-based protocols for large-scale mobile wireless networks composed of a large number of high-speed vehicles. The requirements imposed by our target are high scalability and high-speed mobility emulation while maintaining high accuracy for many hours. To satisfy this, we first introduce a distributed architecture then propose an approach 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 processor clocks by using IEEE 1588 PTPv2. Intensive experiments on the performance of the latest version of our prototype emulator show that (i) high-speed mobility emulation up to 200 m/sec with 0.1 M accuracy, (ii) packet delay emulation with 100 μsec accuracy, and (iii) time-stamps based measurement of elapsed time spent by test nodes with 100 μsec accuracy have been achieved. Our proposed emulator functioned well in an experiment with a simple protocol implementation for car-to-car/infrastructure communication.