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Contact traces collected in real situations represent a popular material to assess the performance of a Delay Tolerant Network. These traces usually require some preprocessing to be fully usable. Especially, several assumptions can be made prior to performing the statistical analysis of contact and inter-contact times. We first classify these assumptions, and analyze their impact on the statistical characterization of three well-known datasets. We also identify some pitfalls in dataset analysis that might strongly influence the conclusion made by the experimenter. Based on our own experience, we subsequently propose a preliminary checklist to help researchers avoid undesired ambiguities or misunderstandings in further studies.

In this paper, we investigate receivers for Vehicular to Vehicular (V2V) and Vehicular to Infrastructure (V2I) communications. Vehicular channels are characterized by multiple paths and time variations, which introduces challenges in the design of receivers. We propose an algorithm for IEEE 802.11p compliant receivers, based on Orthogonal Frequency Division Multiplexing (OFDM). We employ iterative structures in the receiver as a way to estimate the channel despite variations within a frame. The channel estimator is based on factor graphs, which allow the design of soft iterative receivers while keeping an acceptable computational complexity. Throughout this work, we focus on designing a receiver offering a good complexity performance trade-off. Moreover, we propose a scalable algorithm in order to be able to tune the trade-off depending on the channel conditions. Our algorithm allows reliable communications while offering a considerable decrease in computational complexity. In particular, numerical results show the trade-off between complexity and performance measured in computational time and BER as well as FER achieved by various interpolation lengths used by the estimator which both outperform by decades the standard least square solution. Furthermore our adaptive algorithm shows a considerable improvement in terms of computational time and complexity against state of the art and classical receptors whilst showing acceptable BER and FER performance.

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