Wireless Sensor Network Environment
A wireless sensor network is composed of a large number of sensor nodes and one or more sink nodes (base stations). The sensor nodes are deployed inside the area of interest to collect useful information from the surrounding environment and report it to a base station located generally at the extremity of the area of interest for example, the sensor nodes can monitor and report certain events like the movement of objects. The role of the base station is to gather the information sent by the sensor nodes and send it back to the user (control node), and eventually send queries to the sensor nodes.
Wireless sensor network may be static or dynamic. In static wireless sensor network senor nodes are fixed where as in dynamic wireless sensor network nodes are moveable. Nodes in the network may be deployed either randomly or manually, it depends on the application. Sometimes there are more than one sink nodes in the network especially when the coverage area is very large.
Normal Data Transmission Process
In Wireless Sensor Network, data transmission is a task of transmitting the sensed data form source node to sink node. It requires a routing approach to determine the path for transmitting the data and along this path from source node to destination node intermediate nodes relay the data packets. In wireless sensor network data collection is defined as a process of gathering the sensed data from different sensor nodes at the sink node or base station, from where the collected data is transferred to the user. Figure shows the basic process of data transmission and data collection.
Data Transmission with Aggregation
During the data transmission from source node to sink node , data is also aggregarted at the intermediate nodes or relay nodes. In the aggregation process the relay node aggregates its own data with the data that it has received from its children or other nodes after that this relay node transmit this aggregated data to its parent or its successor node.
