Delay Analysis of Physical-Layer Key Generation in Dynamic Roadside-to-Vehicle Networks

Secret key generation by extracting the shared randomness in a wireless fading channel is a promising way to ensure wireless communication security. Previous studies only consider key generation in static networks, but real-world key establishments are usually dynamic. In this paper, for the first time, we investigate the pairwise key generation in dynamic wireless networks with a center node and random arrival users (e.g., roadside units (RSUs) with vehicles). We establish the key generation model for these kinds of networks. We propose a method based on discrete Markov chain to calculate the average time a user will spend on waiting and completing the key generation, called average key generation delay (AKGD). Our method can tackle both serial and parallel key generation scheduling under various conditions. We propose a novel scheduling method, which exploits wireless broadcast characteristic to reduce AKGD and probing energy. We conduct extensive simulations to show the effectiveness of our model and method. The analytical and simulation results match each other.