Infrastructure-Less Vehicle Traffic Density Estimation via Distributed Packet Probing in V2V Network

In this paper, we address the problem of vehicle traffic density estimation without relying on infrastructure cameras or sensors on the road. Previous infrastructure-less approaches still require some prior knowledge on the road infrastructure, e.g., via road topology map. We seek a lightweight estimation method based only on vehicle-to-vehicle (V2V) communication, i.e., without using any prior knowledge. The main objective of this paper is to examine traffic density through simple yet efficient packet probing within a survey time period and obtain a snapshot of the traffic density distribution map. We propose an
on-demand vehicle sampling
algorithm that makes a probing packet at a vehicle (i.e., sampler) keep sampling to explore the local traffic density on a cell basis. If a current sampler does not operate as an efficient carrier, the packet selects another one as the next sampler via
inner-relaying
and
outer-relaying
procedures. To effectively adapt the level of granularity of traffic density depending on the remaining survey time, we present an
adaptive cell sizing
algorithm. Further, we extend the sampling activity to multiple vehicle samplers by making them aggregate their collected information and also negotiate their future areas to explore. Within a designated deadline, multiple samplers collaborate for more accurate and fast traffic density estimation. By doing so by iterations till the given survey deadline, we can gather a complete view of traffic density estimates based on multiple sources where some areas have more detailed information, whereas others do less. Experiments with a real trace-driven simulation demonstrate that our proposed algorithm effectively estimates the distribution of traffic density considering local traffic conditions compared to other counterpart algorithms, with a factor of up to 9.5.