# A Survey of Autonomous Vehicles: Enabling Communication Technologies and Challenges
## 2 Literature Review
In addition, another benefit of the IEEE 802.11p/DSRC is the outside-the-context of a basic service set (OCB) mode [27; 28]. The OCB mode allows communication without authentication/association and as a result offers lower latency which is necessary for safety-critical applications. However, this may result in severe security issues [27]. Finally, for the long-range communication, from a 100 m to 5 km, Third Generation Partnership Project's (3 GPP's) long-term evolution (LTE)-Advanced (LTE-A) pro with its Cellular-V2X capabilities and 5G-NR have emerged as the key technologies [29; 30; 31; 32; 33]. These technologies provide ubiquitous coverage and high data rates and can support low-to-medium latency requirement. However, they are not suitable for safety-critical applications because the latency varies between 50 and 80 ms depending on the cellular traffic load [34]. \begin{table}
\begin{tabular}{p{113.8 pt} p{284.5 pt}} \hline \hline [PERSON] et al., 2008 [23] & The network protocols from the physical to the transport layer are analysed, and the security aspects for V2V communication are mentioned in detail. \\ \hline [PERSON] et al., 2009 [25] & DSRC is developed for V2V and V2I communication. Characteristics, mechanism and the application of DSRC are explained. Security threats and congestion issues are discussed. \\ \hline [PERSON] et al., 2010 [35] & GPS enabled channel sounding system that can predict the multipath and doppler shift for an adaptive OFDM vehicular communication system is developed. 5.9 GHz results in serious multipath and doppler shift issues as compared to the results obtained at 700 MHz band. \\ \hline [PERSON] et al., 2010 [36] & ZigBee technology is combined with infrared sensors to detect and validate the vehicles on the intersections. They proposed model utilised ZigBee technology to help the users to recognise and identify the vehicles for security clearance. \\ \hline [PERSON] 2011 [26] & Development and deployment of DSRC standards (IEEE 1609.\(x\)) is carried out in the United States. Amendments to IEEE 802.11p for wireless access in vehicular environment (WAVE) is proposed for network services, security and multi-channel operations. \\ \hline [PERSON] et al., 2012 [28] & Channel switching is proposed by IEEE 1604.4 will allow the DSRC technology to support multi-channel operations. Analysis on beaconing with the OMNeT++ simulator is presented. \\ \hline [PERSON] et al., 2013 [29] & First time classification based on range such as “short-range”, “medium-range” and “long-range” is done considering the available communication technologies. \\ \hline [PERSON] et al., 2014 [37] & Distributive system for an AV is proposed which reduces computational complexities and modularity. AUTOSAR software application system is proposed. \\ \hline [PERSON] et al., 2015 [38] & DSRC and LTE technologies are combined to produce the heterogenous vehicular network (HetVNet) model. HetVNet models combines the advantages of both DSRC and LTE technologies. Characteristics of MAC and network layers are also proposed for this model. \\ \hline [PERSON] et al., 2015 [39] & Proposed Bluetooth model is validated by over several road experiments in which the vehicle is supposed to move at high speeds and establish connection with its road-side units. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Related work.