## 2 Literature Review  
Cooperative communication strategy for vehicular networks is one of the most commonly used techniques in different manners to enhance the link reliability in a vehicular network and also improve the overall system performance under different environmental conditions. Cooperative communication strategy for vehicular networks is proposed in [13] to explore the combination using V2I communications, and V2V communications, mobility of autonomous vehicles, and cooperation among autonomous vehicles and infrastructure to improve the capacity of the vehicular networks. In addition, the use of cooperative V2X downloading was a typical solution of driving experience [14], in order to achieve better energy efficiency, low emissions and resource sharing. Moreover, the reliability and effectiveness of V2X communication greatly depends on communication architecture, and authors in [15] proposed a D2D communication approach to reduce the latency by offering direct vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. The implicit cooperative positioning (ICP) algorithm that exploits the V2V connectivity in an innovative manner, avoiding the use of explicit V2V measurements such as ranging, was investigated in [16] to enhance the autonomous vehicle localization accuracy. Additionally, to improve road traffic efficiency in cooperative vehicular networks, a new algorithm was presented in [17], combining both clustering and cluster-head autonomous vehicles (CHVs) cooperative communication for reducing traffic congestion. The design of cooperative adaptive cruise control (CACC) to regulate the longitudinal motion of connected and automated vehicles is presented in [18] to improve vehicle safety and mitigate mixed traffic perturbs. In vehicular communication, improving the system performance is an important issue, which is always affected by the accurate representation of the real network topology by the vehicular mobility model [19]. Clustering algorithm in vehicular networks can also contribute to the improvement of the unstable V2V connectivity caused by high-speed vehicle movement [20]. Additionally, the packet delivery rate can be maximized by using a new model called sectorised relay-assisted vehicle-to-vehicle communication (SR-V2 VC) [21]. To overcome the problem of current resource constraint, stochastic dynamic programming (SDP) is employed as a tool to analyze and solve network resource constraint and allocation issues of resources in vehicular ad hoc networks [22]. In addition, the massive multiple-input-multiple-output (MIMO) architecture is attractive to multiple vehicles on the road for V2I, as it is one of the promising solutions to meet the requirements of vehicular communication and it can significantly improve the system spectrum efficiency and energy efficiency [23]. Furthermore, for system performance improvement, [24] developed a new V2V communication scheme to enhance system power control, improving the throughput and fairness index. Moreover, for system reliability, [25] extended a multi-hop relaying into vehicular communication in highways by investigating a transmission scheme where traveling vehicles are allowed to relay signals via neighboring vehicles to the final destination. In addition, a new proposed model based on V2V communication was proposed in [26] to overcome the problem of traffic jams and decrease the travel time for any emergency vehicle. Additionally, it aims to enhance the system performance of vehicular communication. This paper aims to establish an adaptive AV communication, based on using optimization technique to ascertain that the communication between AV2X is reliable. This will be achieved by finding, based on the required QoS, the required best vehicle position that AV should communicate with to efficiently obtain specific road information, and send information to other vehicles or to everything (V2X).