Wireless Sensor Networks

232 Chapter 6 Sensor Network Databases

datum as follows: for the first d zone bits, the i

th

bit is set to 0 if the

i

th

attribute is in [0,0.5]; otherwise it is 1. This process then repeats

on the next d bits of the partition by looking at the second bit of the

attribute value, meaning if the attribute is in [0, 0.25] or [0.5, 0.75],

then the bit is 0; otherwise it is 1. This continues until all the zone

code bits are specified.

2

Essentially, the hashing uses the values of

the attribute in a round-robin fashion on the zone tree to generate a

zone code for the data, similar to a k-d tree.

Inserting data amounts to computing the hash function to deter-

mine