Geometry based Inter Vehicle Distance Estimation for Instantaneous GPS Failure in VANETs

Abstract

Localization in Vehicular Adhoc Networks (VANETs) has witnessed significant attention due the instantaneous failure of Global Positioning System (GPS). Performance of Intelligent Transport Systems (ITS) applications is based on efficient and reliable information dissemination techniques. Efficiency and reliability of information dissemination is dependent on the availability of accurate location information about vehicles. Most of the localization techniques suggested in the past are based on either real time radio signal measurement or Road Side Unit (RSU). Signal measurement is performed in terms of Time of Arrival (ToA) or Received Signal Strength Indicator (RSSI) which is susceptible to measurement error due to the high mobility of vehicles in vehicular traffic environment. Availability of RSU can not be guaranteed. This paper proposes a Geometry based Inter Vehicle Distance (Geo-IVD) calculation techniques which can be utilized for information dissemination in VANETs. Geo-IVD is a cooperative technique which utilizes past and present knowledge about the vehicle. It utilizes mathematical geometry to calculate present unknown location of a vehicle. More specifically, Geo-IVD find the current unknown location of a vehicle considering two cases. In the first case, vehicle's current direction is considered to be the same or opposite from its past direction. In the second case, vehicle's current direction is considered different (other than opposite) from its past direction. Mathematical geometry is utilized to solve the problem of finding current location in both these cases. Simulations are carried out in ns2 and results are comparatively analyzed with that of the state-of-the-art technique: ToA-IVD. Analysis of results attests the superiority of Geo-IVD to the state-of-the-art technique.