Hello scheme for vehicular ad hoc networks: analysis and design

In vehicular ad hoc networks (VANETs), essentially the information of one-hop neighbors is important for data delivery. In a general way, each node broadcasts short packets, i.e., hello packets, to indicate its appearance and establishes a neighbor table for storing neighbor information through receiving others’ hello packets. As a popular approach, it is named as a hello scheme. Determining the validity of the neighbor table, a hello scheme is vital to routing protocols in VANETs. However, a hello scheme with high accuracy and low overhead is severely challenged due to the highly dynamic topology and restricted vehicle mobility in VANETs. To address the issue, it is crucial to optimally configure two key parameters, called as hello interval (HI) and timeout interval (TI), respectively. In this article, a probability model of the hello scheme for VANETs is proposed. It is used to analyze factors affecting the two key parameters. Depending on derivation results, an effective local information-based adaptive hello scheme (LAH) is proposed subsequently. It utilizes the local information, i.e., the variation of neighbor table and received hello packets, to adjust HI and TI adaptively. According to different TI adjustment algorithms, four variants of LAH are designed as LAH-I, LAH-L, LAH-1, and LAH-2. In the end, a comparison between LAH schemes and existing three solutions is conducted to evaluate the performance. Results verify that the proposed LAH schemes are capable of obtaining higher accuracy of neighbor table and lower overhead.