# Analysis and Design of Functional Device for Vehicular Cloud Computing
## 1 Introduction  
Vehicular ad hoc networks (VANETs) are a special mobile ad hoc network for implementing various road traffic applications [1]. It can improve the future development of the transportation system via wireless communication technologies, such as advanced information processing, wireless communication, and device-to-device communication [2; 3]. The highly dynamic topological changes on the network structure and multiple service requirements of users bring significant challenges for VANET applications.  
As we all know, safety message transmissions are critical to ensure road traffic safety in vehicular networks. IEEE standards 802.11p [4] and 1609.4 [5] were developed to ensure reliable communication in the highly dynamic propagation environment of vehicular networks. The original IEEE 802.11p standard was based on a media access control (MAC) sublayer that showed poor performances in provisioning the quality of service (QoS) for different applications in dense VANETs [6; 7]. These problems were particularly important for the reliable transmission of safety messages. Therefore,the multichannel extension IEEE 1609.4 standard was proposed to improve the imperfection in the IEEE802.11p standard.  
In suburban environments, there are spare infrastructures and few vehicles, which is why cooperative relay technologies have been proposed recently as an efficient solution to cope with the many challenges in VANETs [8; 9; 10; 11]. In vehicular networks, road-safety warnings, road-condition reports, and other safety messages are critical for ensuring road traffic safety. To employ a rational use of networks resources, cooperation can be employed to help users take advantage of the broadcast nature of radio frequency transmissions. In this paper, we consider the two-hop transmission case between the source vehicle and destination vehicle. It is possible that there is not a direct link between the source vehicle and destination vehicle. When a source vehicle communicates with a destination vehicle via another vehicle acting as a relay-assisted role, a two-hop vehicular system is formed. We will analyze these two-hop vehicular networks in performance and further realize it in following works.  
Specifically, we study the end-to-end vehicle communication in obeying Dedicated Short Range Communications (DSRC). The assisted vehicle can be introduced to relay transmission messages between two end-to-end vehicles. Then, we analyze the performance of assisted vehicles on a transmission link based on VC. In addition, an optimal path relay selection algorithm is proposed and applied to design an embedded vehicle-enabled device. The major contributions of this paper are as follows:  
1. [leftmargin=*]
2. Employs a novel graph model to model a vehicle-to-vehicle communication scenario which deploys respectively in a two adjacent Roadside Units (RSUs) area.
3. Analyzes link outage probability and gives out expresses depending on SNR in receiving end in end-to-end communication.
4. Designs a functional device for vehicular cloud computing to realize a relay-assisted scheme for vehicular application.
5. Proposes an optimal path relay selection algorithm to cope with the vehicle transmission problem which is beyond the transmission range.  
The rest of this paper is organized as follows. Some related works are introduced in Section 2. Section 3 provides the system model of amplify-and-forward (AF) relay-assisted vehicular networks. Based on the Section 3, Section 4 discusses the specific performance analysis on the probability of an outage with a directing communication channel and relay-assisted communication channel. Whereafter, a relay-assisted scheme for vehicular networks is proposed in Section 5. In Section 6, the simulation results reveal that the relationship between the outage probability and the SNR are evaluated to confirm the suitability of the proposed relay-assisted scheme. Finally, Section 7 summarizes and concludes this paper.