A comparison of various vehicular ad hoc routing protocols based on communication environments
Proceedings of the 7th International Conference on Ubiquitous Information Management and Communication
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In a broadcasting task, source node wants to send the same message to all the other nodes in the network. Existing solutions range from connected dominating set (CDS) based for static networks, to blind flooding for moderate mobility, to hyperflooding for highly mobile and frequently partitioned networks. The only existing protocol for all scenarios is based on some threshold parameters (which may be expensive to gather) to locally select between these three solution approaches. Here we propose a new protocol, which adjusts itself to any mobility scenario without using any parameter. Unlike existing methods for highly mobile scenarios, in proposed method, two nodes do not transmit every time they discover each other as new neighbors. Each node maintains a list of two hop neighbors by periodically exchanging ‘hello’ messages, and decides whether or not it is in CDS. Upon receipt of the first copy of message intended for broadcasting, it selects a waiting timeout and constructs two lists of neighbors: neighbors that received the same message and neighbors that did not receive it. Nodes not in CDS select longer timeouts than nodes in CDS. These lists are updated upon receipt of further copies of same packet. When timeout expires, node retransmits if the list of neighbors in need of message is nonempty. ‘Hello’ messages received while waiting, or after timeout expiration may revise all lists (and CDS status) and consequently the need to retransmit. This provides a seamless transition of protocol behavior from static to highly mobile scenarios. Our protocol is compared to existing solutions. It was shown to be superior to all of them in number of retransmissions and reliability.