# Evolution of V2X Communication and Integration of Blockchain for Security Enhancements
## 4 Edge Computing for V2X Communications
It works in a centralized manner, where the high computation mobile applications are offloaded in the central cloud computing. It is not efficient and not scalable to handle huge amount of vehicular network data. Some of the drawbacks of MCC are as follows. (a) It works in a centralized manner that impose significant costs in terms of energy, bandwidth and time while transmitting data from the vehicles to the clouds or vice versa. (b) It is difficult to manage and update the mobility and location distribution information in real time. (c) MCC servers cannot extract the real time information from the vehicles due to multiple hops from vehicles to RSU to the cloud. As a result, it degrades the user QoS. In 5G-enabled vehicle communications one of the key criteria is low latency. MEC can become a key infrastructure in 5G networks by bringing certain core functionalities close to the edge devices [40]. A detailed comparison between MCC and MEC is given in Table 6.  
The authors in [41] integrated the two promising technologies of MEC and Nonorthogonal Multiple Access (NOMA) technologies in 5G V2X to provide extensive connectivity and to support safety-critical and traffic-efficient applications to deal with things, such as road accidents. The integration of MEC and NOMA provides energy-efficient edge computing that copes with the increasing requirements of ubiquitous connectivity. It minimizes the latency between the edge nodes and the MEC. The existing vehicle networks comprise of heterogeneous physical infrastructure and support different network connectivity components with distinct memory and storage capacities, such as access points, end nodes, and edge routers. The MEC enabled vehicular networks consist of a macro cell equipped with computing server to carry out resource-intensive tasks. The RSU and Wi-Fi AP can also be connected to the macro cell. However, the existing cellular system is based primarily on orthogonal multiple access leading to low speed vehicle connection due to the restricted bandwidth [42]. In 5G, NOMA is proposed in order to give large connectivity and minimize access collisions in bandwidth-limited networks like cellular and vehicular networks to allow non-orthogonal channel access through multiplexing either by power domain or code domain. The macrocell transmits signals to several vehicular users and divides the bandwidth into multiple sub-channels in NOMA-based communications between vehicular nodes and macro cell. The vehicular nodes can utilize multiple sub-channels to send the data at a higher data rate. It helps different users to share frequency resources in a non-orthogonal fashion, with the key benefits of increasing bandwidth, connectivity, and energy-efficiency. In 5G, the macrocell behaves as (1) a global router, (2) MEC server, and (3) Software Defined Network (SDN)-based local controller [43]. The authors in [41] aimed to optimize the achievable transfer efficiency by seamlessly combining both cellular and RSU connectivity to offload network traffic by leveraging NOMA and MEC technologies in vehicular communications. The offloading decision is based on a utility function calculation associated with server rewards for message size, offloading costs and message delay. The detailed heuristic system built on NOMA-based offloading system enabled by MEC for vehicular networks can be found in [41].