Content registration in VANETs— saving bandwidth through node cooperation

Search indices for distributed information are an important building block for many mobile, decentralized applications. However, the network load caused by nodes registering their information in the index can become quite significant especially in mobile networks like vehicular ad-hoc networks (VANETs), where nodes need to register periodically due to their mobility. Our goal in this paper is to encode this registration information as efficiently as possible. For this purpose, we first analytically study hash keys and Bloom filters as alternative encoding types of nodes´ registration data. It turns out that in many situations, Bloom filters are more bandwidth efficient than hash keys, and that they are even more efficient when nodes cooperate. Many such forms of cooperation are conceivable; we define one specific scheme targeting metropolitan VANETs. Our accompanying simulation study shows that this first algorithm already allows for large bandwidth savings in content registration, compared to the alternative of registering hash keys.