9.5 CELL-BASED DISTRIBUTED AIR INDEX FOR SPATIAL DATA
This section presents cell-based distributed air index (CEDI) for energy conservative processing of window query with error resilience against various link error sources on the wireless channel and short data waiting time .
9.5.1 Design Goals for CEDI
- Linear structure: To support linear access pattern of the mobile clients to the wireless channel, CEDI is designed with table-formed linear structure.
- Reduction of the size of index: To reduce the size of index, CEDI is designed to hold only the pointers to data groups by partition of the data space and to eliminate pointers to data items on the wireless channel from it. Instead, CEDI provides the scheme to compute pointers to data items. Also, CEDI is designed with distributed indexing scheme to reduce its size.
- Energy conservation: To reduce the energy consumption of mobile clients, CEDI adopts the scheme filtering out queried data items with the original coordinates of data items in the index before accessing data items. Therefore, the filtering scheme removes listening to redundant data items. Also, CEDI is designed to enable the mobile clients to reduce the index listening time by reducing its size and to decrease the number of indexes accessed during query processing.
- Shrunken access time: CEDI adopts distributed indexing scheme to shrink access time by reduced probe wait. Also for the same goal, CEDI is designed to support multiple access paths to desired data items ...