Improving QoS of VANET Using Adaptive CCA Range and Transmission Range both for Intelligent Transportation System

Connectivity and spatial frequency reuse are very important performance influencing factors in Vehicular Ad-hoc NETwork (VANET). In proposed work connectivity in VANET is measured in terms of Vehicular Average Connected Coverage ( VACC ). Interference on road is measured in terms of Average Highly Interference Region ratio ( AvgHIR ). A new Adaptive Transmission and Clear Channel Assessment (CCA) Power scheme (ATCCAPsch) is proposed. ATCCAPsch varies Transmission Range (TR) along with CCA range to improve VACC , AvgHIR , spatial frequency reuse and hence overall QoS performance of VANET. ATCCAPsch performs its operations based on selected threshold “MINimum Transmission Range of Vehicle ( m i n T R v _ s e l )” and “Required Number of Neighbours ( R N N g b sel )”. Comprisal of m i n T R v _ s e l and R N N g b sel is done in the definition of VANET’s Multi-Objective optimization Problem (VANET-MOP). VANET Multi-Objective optimization Model (VANET-MOM) is defined and implemented to solve VANET-MOP to determine R N N g b sel and lower bound of m i n T R v _ s e l ( l b h v h _ m i n T R v _ s e l ). VANET-MOM incorporates ATCCAPsch in another newly proposed algorithm “VATCCAPschSim” to evaluate VACC and AvgHIR . Multi Objective Optimization (MO-Opt) tool “gamultiobj” is used to serve the purpose. Performance of proposed ATCCAPsch is verified in NS-3 simulator for single channel and infrastructureless VANET. ATCCAPsch decreased mean delay per hop by 1.86, 25.9 and 16.8% for given MAXimum Transmission Range of Vehicle ( m a x T R v ) 250, 400 and 1000 m resp. as compared to Fixed Transmission and CCA Power SCHeme (FTCCAPsch). ATCCAPsch is also enhancing other Quality of Services (QoS) like packet delivery ratio, delay and jitter of VANET.