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Abstract-Wireless links are typically modeled in isolation as independent and parallel links. However, in reality, there is often a correlation in defects and impairments between collocated links. The spatial correlation of shadowing among proximate wireless links has been frequently observed. Although different types of correlated shadowing models have been proposed for wireless channels, these models are not present in popular network simulators. Ignoring such correlations results in the diversity of adjacent links being over-estimated. Our hypothesis is that this could lead to incorrect results when evaluating the performance of wireless systems and network protocols. In this paper, the ns-3 simulation environment has been enhanced with a prototype correlated shadowing model developed in our previously published work. We study the end-to-end packet delivery ratio and delay in wireless sensor networks using both correlated and independent propagation models. Simulation results show that correlated and independent shadowing models produce significant differences in network performance. Moreover, we compare the complexity of different modeling options. It is shown that this correlated propagation model in ns-3 can improve simulation realism without inducing any considerable degradation of scalability.

Abstract-Shadowing losses on proximate wireless links have been experimentally proven to be highly correlated in various scenarios. However, most of the existing works on the reliability modeling of Wireless Multi-Hop Networks (WMHNs) assume independent link shadowing. Neglecting shadowing correlations could lead to inaccurate network simulation results and unreliable wireless system design. In this paper, we present a more realistic reliability model of WMHN that incorporates correlated link shadowing. In particular, we use the correlated shadowing model that was developed in our previous work. This model enables the efficient generation of spatially correlated shadowing. It has been proved to agree well with the literature in terms of statistical properties. The proposed network model allows us to predict the reliability metrics of WMHNs and study network designs that can lessen the effect of correlated shadowing. Numerical results indicate that it is important to use the correlated shadowing model when evaluating the reliability of densely deployed large-scale multi-hop networks. We also present some numerical results to show the influence of shadowing correlation on redundant node deployment. This paper makes a small but fundamental step towards reliable wireless multi-hop network design in the context of correlated link shadowing.

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