# Analysis and Design of Functional Device for Vehicular Cloud Computing
## 2 Related Works  
Recently, many works have been researched on relay selection applications due to its advantages in vehicular networks [12; 13; 14; 15]. Reference [12] proposed a power allocation and relay selection scheme limited by outage probability to increase the performance of vehicular networks. Reference [13] reported on cooperative diversity with relay selection over cascaded Rayleigh fading channels in dual-hop decode-and-forward (DF) vehicular networks. Reference [14] proposed the optimal relay scheme by considering the vehicle location and link capacity in vehicular networks. However, these relay schemes also brought complicated data frame communication process and computing on performance analysis. The cooperative communication tailored as vehicular cooperative media access control (VC-MAC) is designed in Reference [15] to maximize the system capacity. The current results are within the limits of congestion control issues, the Rayleigh fading channel assumption, the maximum end-to-end capacity, and cooperation downloads for vehicular networks. Experimental and theoretical studies have researched appropriate fading models under the condition of a Rayleigh fading channel for inter-vehicular channels.  
In cascaded rayleigh fading, the performance of relaying for vehicular cooperative strategy assisted by a RSU or relay which acts as relay is investigated [16]. It carried out a further comprehensive analysis based on Reference [17] which only considers RSUs which act as relays. Reference [18] proposed a vehicle-to-vehicle communication protocol for cooperative collision warnings. However, they mainly consider a low latency when delivering emergency warnings in various road situations. The QoS of vehicular networks, which considers the possibility of an outage during emergency warnings communication, is not considered. To improve QoS, decentralized relay-assisted multiuser multiple-input multiple-output (MIMO) approaches are widely used in References [19; 20; 21; 22]. Reference [23] mainly studied the promising effects of cooperative transmissions in radio frequency communications. The two-transmitter case was considered, but it did not consider the direct transmission case between the source vehicle and destination vehicle. The introduction of vehicular cloud computing has promoted the development of related vehicular technologies [24; 25]. In Reference [26], two opportunistic relay selection algorithms were proposed and the results showed that the selected relay had an impact on the interference generated in the network and the stability of the relay. To minimize these interference, the authors proposed a suitable relay selection scheme [27]. These works also did not consider the complicated calculations and transmission delay caused by the analysis.  
Real-time data transmission response was the key feature of DSRC in a rapidly changing environment. Data dissemination was one of most critical issues for vehicular traffic environments [28]. These real-time data applications required complex computations and brought challenges in implementing applications for vehicle devices [29; 30]. Recently, many researches adopted cloud computing to address these challenges for vehicle devices. Reference [31] proposed a geocast routing protocol for the reliable and efficient dissemination of data due to an increase in vehicular applications favoring geocasting. Reference [32] designed a beaconless packet forwarding protocol by considering the vehicle direction and link quality during packet transmission. However, these protocols suffered from higher end-to-end delays in vehicular networks.