Energy conservation and access efficiency are two fundamental though competing goals in broadcast wireless networks. To tackle the energy penalty from sequential searching, the interleaving of index with data items has been proposed. Although, quite important contributions exist on providing broadcast indexes, they have one or more of the following problems. Firstly, all of them assume total ordering among broadcast data, and none considers the more general case of partial ordering. Secondly, they are balanced structure, which does not fit the "linear (one-dimensional) structure" of the wireless medium, in which imbalanced structures may offer significant advantages. Thirdly, they do not take into account the skewness in the access pattern, which prohibits larger performance gains to be reaped. Finally, they require all index items to be of equal size, which may not always give the optimal performance. To cope with all these problems, we introduce a new imbalanced tree-structured index. The new index is shown to be a generalization of two previously proposed high-performance indexes, and it introduces for the first time the problem of indexing partially ordered broadcast data. We present an experimental analysis of the proposed method, contrasting it with competing techniques. The analysis exhibits the efficiency of the proposed index in reducing the energy consumption without noticeably worsening the access latency
['Dimitrios Katsaros', 'Nikos Dimokas', 'Yannis Manolopoulos']
Generalized Indexing for Energy-Efficient Access to Partially Ordered Broadcast Data inWireless Networks