Data Gathering in Sensor Network

Pre-requisites: WSN, Sensor Network Architecture

The objective of data gathering in the sensor network is to transmit the sensed data from each sensor node to a base station. In other words, data gathering is used to maximize the number of rounds before the node dies and the network becomes inoperable. Here one round indicates the base station collecting data from all sensor nodes once. It is also used to minimize energy and reduce delay in the sensor network. 

Different types of processes in data gathering are listed below:

1. Data Transmission: All the sensor nodes transmit their data directly to the base station. But there are prominent disadvantages to this process. 

• It is expensive in terms of energy consumed. More the energy consumed, the more the cost increases,
• Media delay is also large. Transmitting information to the base station from a node that is located far away from it would take time.
• Performs poorly as it transmits data directly to the base station.

2. Power-Efficient Gathering For Sensor Information System (PEGASIS): It is an enhancement over Low-energy adaptive clustering hierarchy (LEACH) protocol. It is based on the assumption that all the sensor nodes know the location of every other node. 

Goals Of PEGASIS:

• Minimize node transmission distance.
• The lower overhead of broadcasting.
• Minimize the number of messages that need to be sent to the base station.
• Equal distribution of energy consumption across all nodes.

Data Gathering With PEGASIS:

• A greedy algorithm is used.
• A chain of sensor nodes is constructed starting from the farthest node in the base station.  

Here C and F are the distant nodes, so the transmission starts from them to the nearest node in their region which is node B for node C and node D for node F. This kind of transmission continues until it reaches the base station. 

3. Binary Scheme: It is a chain-based scheme in which nodes are classified into different levels. It is not applicable for non-CDMA sensor nodes. At each level, the number of nodes is reduced from the previous level. Below is an explanation of how the binary scheme works. 

There are seven sensor nodes followed by a Base Station in the above diagram. At the first level, S1 sends data to S2, S3 sends data to S4 and S5 sends data to S6. At the end of the first level, the data is stored in S2, S4, and S6.

 So at the second level, S2 sends the stored data to S4 and S6 sends the stored data to S7. At the end of the second level, S4 has the data stored from S1, S3, and S2 and S7 has the data stored from S5 and S6. 

At the third level, S4 sends the data to S7.

At the fourth level, finally, all the data from the seven sensor nodes reaches the base station when S7 transmits data to the base station.

4. Chain-Based Three-Level Scheme: It is applicable for non-CDMA sensor nodes. Chain is constructed and it is divided into a number of groups to space out simultaneous transmission. 

In this diagram, there are groups in which there are clusters of nodes and each group has a leader node that gathers the data from the nodes in the same group and transmits it to a node in a group at a higher level. This creates a chain-based transmission mechanism to the base station.

Application of Data Gathering in Sensor Network:

1.Environmental checking: Information gathering in sensor organizations can be utilized for ecological observing, like estimating temperature, stickiness, air quality, and other natural variables. This can be helpful in applications, for example, environment checking, farming, and contamination control.

2.Industrial mechanization: In modern settings, information gathering in sensor organizations can be utilized for observing gear, distinguishing flaws, and streamlining activities. This can prompt superior efficiency, diminished personal time, and expanded security.

3.Smart homes and urban areas: Information gathering in sensor organizations can be utilized to make homes and urban communities more astute. For instance, sensors can be sent to recognize inhabitance, lighting levels, temperature, and other natural elements. This information can be utilized to advance energy utilization, further develop security, and improve the personal satisfaction.

4.Health checking: Information gathering in sensor organizations can be utilized for wellbeing observing, like observing crucial signs, following medicine adherence, and distinguishing falls. This can be especially helpful for older or handicapped individuals who require ceaseless consideration.

5.Disaster reaction: in case of a cataclysmic event or crisis, information gathering in sensor organizations can be utilized to screen and answer what is going on. For instance, sensors can be sent to recognize seismic tremors, floods, or flames, and this information can be utilized to facilitate salvage endeavors and limit the harm.