# Context-Aware Pending Interest Table Management Scheme for NDN-Based VANETs
## 5 Context-Aware Pending Information Table Entry Management (CPITEM) Scheme
### Non-Safety PITE Priority
#### 5.2.4. PITE Priority
Furthermore, the CACN features a coding scheme that represents the majority of the content name components, allowing for addressing communication and storage complexity [9]. To investigate the impact of shared communication channels, a highway traffic scenario is used to simulate the performance of the HLLR [11; 12; 13] and proposed CPITEM scheme. The highway scenario consists of a 10 km, four-lane road. In this scenario, the consumer vehicles transmit the Interest message to the vehicles in its neighbourhood. Two safety and four non-safety applications are considered. Consumers are requesting content by sending Interest messages, whereas the producers who have the required content send the relevant Data messages after receiving the Interest messages. Consumers and producers are both mobile. Six applications types are taken into account: post-crash application, work-zone application, file sharing application, commercial advertisement application, parking availability application, and traffic navigation map application. Both schemes consider a pull-based scheme for obtaining the required content from the content holder. Just like in the work of [9], we assume that each vehicle is equipped with GPS, via which it obtains its location. Common parameter settings for all the experiments are depicted in Table 2. Producers, consumers, and forwarders are all mobile. Speed is assigned randomly to vehicles. Due to the variation in speed, a dynamic environment is generated that limits inter-connectivity between vehicles for a longer period of time. \begin{table}
\begin{tabular}{l c c} \hline \hline \multicolumn{1}{c}{**Parameters**} & \multicolumn{1}{c}{**Value**} \\ \hline Vehicle Radio Range (\(RR_{\text{max}}\) ) & 150 m & \\ \hline Producer Vehicle & \multicolumn{3}{c}{7 (unless specified otherwise)} \\ \hline Propagation Loss Model & \(\bullet\) & _Nakagami_ propagation loss model \\  & \(\bullet\) & Range propagation loss model \\ \hline Propagation Delay Model & & \\ \(\bullet\) & Highway & \(\bullet\) & Constant speed propagation delay model \\ \hline Producer vehicle placement & \(\bullet\) & Within the initial distance of 1.9 km \\ \(\bullet\) & Highway & \(\bullet\) & Safety producers (1.1 km) (located at a distance of 1.5 km and 1.9 km) \\ \hline Network density & \multicolumn{3}{c}{130 vehicles (unless specified otherwise)} \\ \hline Road length & 10 km & \\ \hline Replacement Policy & LRU & \\ \hline Caching Policy & LCE & \\ \hline \(TxPowerStart\) & \(5\) (\(dbm\)) & \\ \hline \(TxPowerEnd\) & \(5\) (\(dbm\)) & \\ \hline PEL & 4 s & \\ \hline Speed Variation & 20 (70–90 km/h) [30; 31] & \\ \hline Consumer vehicle & 8 & \\ \hline Simulation time & 500 s for each experiment & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Common Configuration Parameters. There are seven producers, and each produces content related to a specific application. All the contents related to one application are stored on one producer. The producers are located at different positions on the highway between 1.1 km and 2.4 km. Safety content producers are located between 1.1 km and 1.35 km. Considering the time and spatial validity requirements of the applications, the producers of the safety content are placed closer to consumers (1.1 km) compared to the non-safety content (located at a distance between 1.3 km and 2.4 km). Therefore, the PIT entries for safety content are resolved a little earlier compared to non-safety content. Two safety application contents and five non-safety application contents are considered. In Safety Content Application (SCA) scenarios, the consumers are sending Interest messages to request safety content related to applications SCA1 (Post crash) and SCA2 (work zone). Considering our proposed CACN scheme, two different safety content names are exploited for safety applications, which include: (i) \(SCAI\) (\(Safety/Local/Text/Post-crash:Head-onCollisions/\dots\)), (ii) \(SCAI\) (\(Safety/Local/Text/Road\)\(congestion:Work\)\(Zone/\dots\)).