Abstract
This letter proposes a Cell-based Hybrid Index (CHI) for energy conserving k Nearest Neighbor search on air. The proposed CHI provides global knowledge on data distribution for fast decision of the search space and local knowledge for efficient pruning of data items. Simulations show that CHI outperforms the existing indexing schemes in terms of tuning time and energy efficiency. With respect to access time, it outperforms them except the distributed indexing scheme optimized for access time.