Wireless Propagation Characteristics for Vehicular Ad-Hoc Networks in Motorway Environments Características de propagación inalámbrica para redes Ad-Hoc vehiculares en autopistas

This paper presents the measurements and analytical results regarding important characteristics of wireless propagation for vehicular ad-hoc networks in motorway environments, including Doppler Effect, Free Space Signal propagation, path loss and system operating margin. In this work, we employ IEEE 802.11b wireless cards for inter-vehicular communication to analyze large and small-scale propagation models. According to large-scale models, the maximum distance between the transmitter and receiver vehicle is 446 m using 5 dBi omni-directional antennas. Additionally, the feasible System Operating Margin (SOM) of 446 m is greater than 13 dB, which is over the minimum margin recommended. Our results show that the Doppler Effect does not affect the transmission between communication partners at high speeds in small-scale models. Finally, we realize an experiment to validate the results in the worst case scenario, when the transmitter and receiver vehicle are traveling in opposing directions on a straightaway. Results show that at least 8 packets can be relayed when the transmitter and receiver antennas are mountedonautomobiledashboards.