| Popis: |
The exchange of information between vehicles and highway infrastructure also known as vehicle to infrastructure (V2I) communications has been viewed as one solution to lessen some of the problems in transportation. Currently, V2I communication uses ITS band of 5.9 GHz frequency which is more susceptible to attenuation and has propagation coverage limitation. Over the past years, the use of Television white space (TVWS) has gained popularity because of its superior propagation characteristics due to its low operating frequency. In this study, V2I communications in the TVWS spectrum using the IEEE 802.11af compliant devices has been implemented at the campus of the University of San Carlos in Cebu City, Philippines and evaluated in terms of received signal strength (RSS), throughput and packet loss rate as a function of the modulation coding scheme used. The calculated path losses were modeled as log-normal shadowing and path loss exponents between 3.05 to 3.63 were obtained. At a transmit power of 20 dBm coupled with a 14.3 dBi-12-ring Yagi antenna under line of sight scenario, a 3.76 Mbps throughput was achieved at the receiver end that used a 3 dBi omnidirectional antenna. There was a 15% reduction in throughput observed in non-line of sight scenario caused by multipath propagation influenced by trees, vegetation, and buildings present between the transmitter and the receiver. However, the data obtained when V2I communication was established suggests the feasibility of utilizing TVWS for V2I communications in support of the goals of the ITS. |
