# Context-Aware Data Dissemination for ICN-Based Vehicular Ad Hoc Networks
## 2 Related Work  
VANETs are a special instance of MANETs (Mobile ad-hoc networks) with similar features: A lack of fixed infrastructure for communication, self-organization, low bandwidth, and short radio transmission ranges. Therefore, most routing protocols for MANET can be used in VANET, such as AODV (Ad-hoc On-demand Distance Vector) [6] and DSR (Dynamic Source Routing) [7]. Conversely, many VANET protocols are based on ideas and concepts from MANET, but with modifications based on the special characteristics of vehicular networks. DSR uses flooding during the routing discovery phase to find a route to the destination. Flooding performs relatively well when there is a small number of nodes in the network and is easily implemented. However, when the number of nodes in the network increases, the bandwidth needed for one message transmission may increase exponentially. In the wireless environment, this may also cause heavy contentions and collision. Thus, the performance of transmission will decrease markedly. In this paper, the flooding mechanism is used to deliver the messages in the context of ICN, and we concentrate on reducing the number of broadcast messages in order to reduce the overhead and better use the bandwidth. Although most routing protocols for MANET can be used in VANET, some studies [8; 9; 10] have shown that the performance of most ad-hoc routing protocols (e.g., AODV and DSR) degrades when the nodes move quickly and the network is highly dynamic. Therefore, several routing protocols have been proposed for VANET, such as position-based routing [9; 11], broadcast routing [12] and cluster-based routing [11; 13]. Among them, GPSR (Greedy Perimeter Stateless Routing) [14] is one of the best-known position-based protocols. It combines greedy routing with face routing by using face routing to get out of the local minimum where greedy fails. It works well in a free open environment with evenly distributed vehicles. In this paper, we use geographical position information and the greedy algorithm in the context of ICN, since geographical information can be easily obtained from modern navigation systems and street maps. Moreover, packets will make fewer hops between source and destination; therefore, they can have lower latency in general. The context information of VANETs has been discussed in depth [15]. Three categories of contexts--mobility vectors, connectivity ability, and application requirements--have been discussed and considered in the unified architecture called CARAVAN, which aims to solve problems concerning the incremental deployment of VANET. In this paper, we consider the context information covering the three major categories, using few but important parameters in VANET to improve the performance of data dissemination using ICN technology. Some researchers have investigated the advantages and possibilities of using ICN in VANETs. For example, vehicular networks have been considered by the ICN Research Group of the InternetResearch Task Force (IRTF) as a key scenario in which ICNs will play an important role; some challenges and existing work in the area have been outlined in [16]. In [17], the authors made a detailed analysis concerning ICN for connected vehicles. They deemed that information-centric networking could meet the challenging demands of vehicular networks and their evolution because of certain features: Named content retrieval, innate multicast support, and an in-network data caching mechanism. Named Data Networking (NDN) [18] is a pioneering implementation of ICN. Two types of messages--Interest packet and Data packet are introduced to retrieve and respond contents identified by their names. A consumer (i.e., content requestor) requests a content by sending an Interest packet with the corresponding name. Any node hearing the request and having the data (i.e., content holder) can issue a response with a Data packet. A PIT (Pending Interest Table) is used in each intermediate node to record the requests that have not been responded to, which also realizes the multicast function.