Answers for queries are approximate.
??? Query processing in sensor networks focuses on query response time. The
goal of sensor networks is to monitor the status of the factual world, such
as tra?±c accidents, fire accidents and etc. Thus, real-time query processing
is needed and the query results should be returned to users in a timely
manner.
The seventh di?®erence is that, the amount of data from sensors is very
large and not all of the data can be stored. At the same time, limited by the
bandwidth, the processing ability and power of each sensor, the centralized
storage scheme and the calculation are not suitable for sensor networks and not
good for fault-tolerance. To improve the performance and the fault-tolerance
ability, the data management system of sensor networks needs power e?±cient
in-network distributed data processing algorithms to implement e?±cient query
processing and data management.
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Jinbao Li, Zhipeng Cai, and Jianzhong Li
2 Architecture of Data Management System in Sensor
Networks
Four system models will be introduced in this section. They are: centralized
model, semi-distributed model, distributed model, and hierarchical model.
2.1 Centralized Model
In a centralized model, query processing and access to sensor networks are
separated. The centralized approach proceeds in two steps. First, data is extracted
from the sensor network in a predefined way and is stored in a database
located on a central server.
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