Fading Improves Connectivity in Vehicular Ad-hoc Networks
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Connectivity analysis is a crucial metric for network performance in vehicular ad-hoc networks (VANETs). Although VANET connectivity has been intensively studied and investigated under channel models without fading for their simplicity, the connectivity probability provided by these studies does not mimic the real-world scenarios that suffer from channel impairments. However, the connectivity probability was too challenging to be caught by a closed formula due to the emerging complexity associated with the randomness in a fading channel. In this paper, we precisely estimate the connectivity probability using a proposed graph-based algorithm. The results prove that Rayleigh-fading channels reinforce the connectivity compared to no-fading models at the same level of transmitting power and vehicle densities. Using simulations and analysis, we thoroughly investigate these outcomes and their causes providing closed formulas for single-link connectivity and an upper bound for vehicle connectivity under fading conditions. We also exploit the numeric results of the proposed algorithm to deduce an upper bound for the VANET connectivity probability under Rayleigh-fading channels.
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