Distributed Skip Air Index for smart broadcasting in intelligent transportation systems

Wireless data broadcast received a lot of attention from industries and academia in recent years. In any form of a push-based broadcast, access latency and tuning time are vital issues, and in order to address the tradeoff among these competing goals, the broadcasting of indices along with the data is the most viable solution. Currently, two broad indexing families exist: those that exploit some form of a tree structure, and those that are based on some `distributed access on the air´ mechanism. The latter family is the most popular and viable, because it allows for following `air-pointers´ without the need to first find a tree root. The champion method of the distributed air index is the Exponential index which however is not appropriate when the access pattern is skewed, i.e., some data items are more popular than the others. To address this shortcoming, we design a Distributed Skip Air Index (DiSAIn), which exploits access statistics in order to improve average tuning time, while it preserves the access latency equal to that of the original Exponential index. To attest the superiority of the proposed indexing method, we perform a detailed simulation evaluation of the two competing methods.