<p><span style="font-size: small;">Vehicular adhoc network (VANET) adopts or resembles a similar structure of Mobile adhoc network (MANET).</span><span style="font-size: small;">  </span><span style="font-size: small;">The communication in VANET are generally classified into following three categories such as Vehicle to Infrastructure (V2I), Vehicle to Vehicle (V2V) and Hybrid network which is a combination of V2V and V2I network. VANET using the IEEE 802.11p standard has great potential of achieving objectives of Smart intelligent transport system (SITS) for improving transport and road safety efficiency. As more and more services is been provided for V2V based VANET network. It is a challenging task to provide QoS to end user, due to wireless medium that has limited channel availability for transmission. To guarantee QoS and provide efficient network performance, a prioritized MAC need to be designed. Many priority based MAC has been designed in recent times to improve the quality of data delivery to end user. However these do not consider the impact of environment and presence of obstacle which affects the signal attenuation at the receiver end and affecting the QoS of channel availability. To address, this work present an obstacle based radio propagation model, obstacle based CEV (City, Expressway and Village) environmental model and a selective MAC to provide QoS for different services. The proposed model efficiency is evaluated in term of throughput achieved per channel, Collison and success packet transmission. To evaluate the adaptive performance of proposed AMACexperiment are conducted under CEV environment and are compared with existing MAC NCCMA. The outcome achieved shows that the proposed model is efficient in term of reducing Collison, improving packet transmission and throughput performance considering two types of services.</span></p>

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