  Radio applications are increasingly being used in urban environments for
cellular radio systems and safety applications that use vehicle-vehicle, and
vehicle-to-infrastructure. We present a novel ray tracing-based radio
propagation algorithm that can handle large urban scenes with hundreds or
thousands of dynamic objects and receivers. Our approach is based on the use of
coherence-based techniques that exploit spatial and temporal coherence for
efficient wireless propagation and radio network planning. Our formulation also
utilizes channel coherence which is used to determine the effectiveness of the
propagation model within a certain time in dynamically generated paths; and
spatial consistency which is used to estimate the similarity and accuracy of
changes in a dynamic environment with varying propagation models and blocking
obstacles. We highlight the performance of our simulator in large urban traffic
scenes with an area of 2*2 km^2 and more than 10,000 users and devices. We
evaluate the accuracy by comparing the results with discrete model simulations
performed using WinProp. In practice, our approach scales linearly with the
area of the urban environment and the number of dynamic obstacles or receivers.

Signal Processing