**4.3. Tradeoffs of different applications**

86 Wireless Sensor Networks – Technology and Protocols

**4.1. Trade off index TOI** 

**4. Tradeoffs among accuracy, energy and delay** 

**4.2. Applications of WSNs with different criteria** 

and transmission delay in table 1.

**Table 1.** Applications of MRSN

Previous section clearly shows partial aggregation with random pushing rate

the energy consumption, transmission delay and data accuracy. In MRSN, according to applications, delay taken to collect data, energy consumed by each sensor node for communication and data accuracy of the collected data are critical concerns and are in tradeoff each other. Energy, delay and accuracy cannot reach full potential at the same time, but we can achieve the best possible tradeoff between them. To obtain the best trade-off value of practical application, we propose a Trade-Off Index (TOI). In the following subsections, we discuss energy, delay and accuracy of trade-offs in respect of TOI as criteria. Here E denotes total energy consumption, D denotes total delay, Ac denotes data accuracy. α, β, γ indicate the significance of accuracy, energy and delay and larger α, β, γ indicate more significance of energy, delay and accuracy. The smallest TOI value denotes the best data aggregation.

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In MRSN, according to the different applications and objectives, we need different significances for transmission delay, energy consumption and data accuracy. Some application areas need to save energy because it is impossible to replace or recharge the battery. In some applications not only the energy is significant, but also the data freshness, such as in military monitoring and disaster monitoring; however data accuracy is most important in medical utilization and in quality control. According to real application, we formulate some of the applications according to the significances of energy, data accuracy

*E D TOI*

*c*

*D*

*A* (26)

*<sup>i</sup>* can control

In this section, we will investigate the tradeoffs among the applications of which data generation rate is in the range of 0.0001 to 100 events in per second, and here for corresponding to the event generation rate, we define the random pushing rate vectors as the same with event generation rate. We define the random pushing rate vectors as below:

As data generation rate of λ=0.0001, T= [0.0001, 0.0001, 0.0001, 0.0001, 0.0001],

As λ=0.001, set T= [0.001, 0.001, 0.001, 0.001, 0.001], As λ= 0.01, set T= [ 0.01, 0.01, 0.01, 0.01, 0.01], As λ= 0.1, set T= [ 0.1, 0.1, 0.1, 0.1, 0.1], As λ= 1, set T= [ 1, 1, 1, 1, 1], As λ= 10, set T= [ 10, 10, 10, 10, 10].
