# Context-Aware Pending Interest Table Management Scheme for NDN-Based VANETs
## 1 Introduction  
Rapid advancements in various network technologies, such as Wireless Local Area Networks (WLANs) and cellular systems promise to accelerate the advancement of Intelligent Transportation Systems (ITS) [1]. Many cities around the world are experiencing population growth and rapid urbanization, as well as an increase in vehicle traffic relative to road infrastructure. The number of deaths caused by traffic accidents is by far the highest of any category of accidental deaths every year. ITS introduced Vehicular Ad hoc NETwork (VANET) to create a safer architecture for road transportation in order to make the journey safer, less stressful, and more enjoyable [2]. In VANETs, each vehicle relies on the processing, storage, and communication capabilities of On-Board Units (OBUs), which manufacturers are already incorporating into vehicles. As VANET is a critical component of ITS, research academies and industrialists are paying close attention. The VANETs communication capabilities enable vehicles to communicate with one another and with infrastructure (such as a Road-Side Unit (RSU)). The capability of in-vehicle technologyenables a wide range of applications in which vehicles interact and collaborate with one another and with infrastructure. VANET was created primarily to support safety-related applications. Recently, autonomous and coordinated driving applications have emerged as yet another compelling reason to adopt VANETs [3]. In addition, infotainment applications continue to entice drivers who want to exchange multimedia content while driving. In traditional Internet Protocol (IP)-based VANETs, each vehicle must be identified with a unique address, similar to Mobile Ad hoc Networks (MANETs) [3]. The IP communication model is based on host-to-host communications, in which one host requests a resource and others provide it. VANET is an information-centric network, where in most applications the vehicles care about information. Named Data Networking (NDN), which is one of the realizations of ICN, decouples content from producers and retrieves content from the nearest content holder using hierarchically and semantically meaningful names [4; 5]. The closest content holder could be the original content producer or a node with a valid copy of the requested content. By increasing the number of content sources, NDN reduces content delivery delay and thus increases content delivery probability. The NDN architecture is a promising replacement for the TCP/IP architecture [4; 5]. As mentioned before, NDN is a content-centric protocol that focuses on the desired data, not the location of the data. NDN architecture supports mobility. Consumer (content requester) mobility is by default supported in the original design of NDN. NDN allows for assigning unique names to contents that can be used for its search, retrieval, storage, etc. Moreover, NDN supports ubiquitous in-network distributed caching, which allows intermediate routers (vehicles) to cache content to reduce the delay in obtaining content. NDN supports two types of messages: (i) Interest messages and (ii) Data messages. Customers request content by sending out an Interest message. The content holder who has the requested content forwards the Data message after receiving the Interest message. Each node in the native NDN contains three data structures. The Forwarding Information Base (FIB) data structure stores forwarding information by keeping a mapping of content name prefixes and interfaces (Faces) through which Data messages can be forwarded. The Pending Interest Table (PIT) keeps track of all pending Interests and their incoming interfaces that have yet to be served. The content objects are cached by the Content Store (CS) based on a caching policy. In NDN-based VANETs, content is requested by name. Additional information about the requested content may be included in the name. Various VANET applications have multiple, possibly conflicting, and disparate QoS expectations [5; 6; 7; 8; 9].