We present a new conservative event-synchronization protocol, time-based synchronization, for parallel discret-eevent simulation of mobile ad hoc wireless networks. Simulators that use our protocol proceed at a scaled version of real time and send messages that correspond only to transmissions in the simulated network. We show that such simulators can maintain a constant execution time even as the sizes of the networks that they simulate grow. Moreover, we show that these simulators, when executed on a custom parallel architecture, are capable of simulating many networks faster than real time.