Power consumption of sensor node is analyzed in this p aper. In order to analyze the energy consumption, the node model is simulated using Proteus Software tool. The p roposed sensor node ’ s power characteristics are measured by using different combination s of m icroprocessors and sensors. Using this, the energy consumption of the node is calculated. This is a cost - effective method and provide s appropriate power model for specific applications.
Wireless sensor networks technology has various applications such as surveillance and information gathering in the uncontrollable area of human. In order to further increase the applicability in real world applications, minimizing power consumption is one of the most critical issues. Therefore, accurate power model is required for the evaluation of wireless sensor networks [
Hence, by trying different combinations of microcontroller and sensor and measuring their power usage and lifetime [
To capture the power consumption, a digital oscilloscope was set up to measure the voltage v(t) over a series resistor R. A small resistance value was chosen in order to minimize additional voltage drop. The setting is shown below in
Different types of microcontroller are available which have different internal architecture, power consumption, speed and instruction set [
The output of the multiplexer is digital. For the purpose of modulation, it is also multiplied with high frequency sine wave. To avoid abrupt transitions in the modulated wave, the digital output of multiplexer must be smoothened [
An analog-to-digital converter is used to analog signal into digital. The conversion
involves quantization of the input, so it necessarily introduces a small amount of error [
When an analog sensor (e.g. LM 35) is used and microcontroller doesn’t have an inbuilt ADC, an external ADC is used.
Binary Amplitude shift Keying is used in this model (ASK). The advantage of using ASK scheme is that it has a simple modulation and demodulation technique. Since, the output of the sensor node is in burst rather than continuous form, ASK offers a simple transmission scheme within tolerable average probability of symbol error.
Total energy consumed = ∑(power for active mode * active time) + ∑(power for sleep mode * sleep time).
Average power consumed = Total energy/Total time.
Energy supplied from the battery = voltage * current * time.
Lifetime of the sensor node = energy from battery/average power consumed.
By placing the Microcontroller and sensor, the temperature measurement was carried out. The readings were taken using the in-build Oscilloscope. To estimate the lifetime of sensor node, the power characteristics of sensor node were measured by calculating voltage drop across the resistor and calculating the current. This operation was repeated for various Microcontrollers and Sensors at different temperatures. The parameters measured are substituted in the formulae and thus the lifetime of the sensor node can be calculated.
In
The Microcontrollers and sensors are varied and the lifetime of the sensor node was calculated and readings are tabulated in Tables 1-3 respectively.
Figures 3-7 shows the waveforms associated with various Microcontroller and temperature sensors.
Power calculated from the graph, W = 0.6348 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 3938.16 hrs
Lifetime of Sensor Node (in Days) = 3709/24
= 164.09 days
Microcontroller | Sensor | Power consumption (mW) | Lifetime (days) |
---|---|---|---|
ATMEGA16 | DS18B20 | 0.5975 | 174.33 |
ATMEGA16 | LM35 | 0.636 | 163.76 |
PIC16F887A | DS18B20 | 0.6101 | 170.72 |
PIC16F887A | LM35 | 0.6348 | 164.09 |
AT89C51 | DS18B20 | 0.6407 | 162.58 |
AT89C51 | LM35 | 0.6904 | 150.88 |
Microcontroller | Sensor | Power consumption (mW) | Lifetime (days) |
---|---|---|---|
ATMEGA16 | DS18B20 | 0.6225 | 167.34 |
ATMEGA16 | LM35 | 0.657 | 158.55 |
PIC16F887A | DS18B20 | 0.6321 | 164.79 |
PIC16F887A | LM35 | 0.6578 | 158.36 |
AT89C51 | DS18B20 | 0.6617 | 157.42 |
AT89C51 | LM35 | 0.7154 | 145.61 |
Microcontroller | Sensor | Power Consumption (mW) | Lifetime (days) |
---|---|---|---|
ATMEGA16 | DS18B20 | 0.6435 | 161.88 |
ATMEGA16 | LM35 | 0.679 | 163.76 |
PIC16F887A | DS18B20 | 0.6551 | 170.72 |
PIC16F887A | LM35 | 0.6818 | 164.09 |
AT89C51 | DS18B20 | 0.6867 | 162.58 |
AT89C51 | LM35 | 0.7374 | 150.88 |
Power calculated from the graph, W = 0.6407 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 3901.92 hrs
Lifetime of Sensor Node (in Days) = 3901.92/24
= 162.58 days
Power calculated from the graph, W = 0.6904 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 3621.12 hrs
Lifetime of Sensor Node (in Days) = 3621.12/24
= 150.88 days
Power calculated from the graph, W = 0.5975 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 4183.92 hrs
Lifetime of Sensor Node (in Days) = 4183.92/24
= 174.33 days
Power calculated from the graph, W = 0.6101 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 4097.28 hrs
Lifetime of Sensor Node (in Days) = 4097.28/24
= 170.72 days
Power calculated from the graph, W = 0.636 mW
Energy supplied by the battery, E = 5 V * 500 mAh
= 2.5 Wh
Lifetime of Sensor Node (in Hrs) = E/W
= 3930.24 hrs
Lifetime of Sensor Node (in Days) = 3930.24/24
= 163.76 days
The readings were tabulated from Tables 1-3 and using these readings, the Bar Chart representation was plotted and it is shown in
The results of this study reveal that, ATMEGA16 microcontroller used in combination
with DS18B20 digital sensor has the least power consumption, hence the longest lifetime. Further, it is observed that by using differential encoding, power is drastically reduced. By transmitting the difference, the number of bits is reduced. Thus the transmission power is reduced which in turn reduces the overall power consumption. Since this is done in software by the microcontroller, no external hardware is needed.
Also, by processing the data in parallel form i.e., in BCD format, consumed power is less in comparison to serial processing. Since, the data from the sensor are inherently in BCD format. This project can further be extended by trying more combinations of microcontrollers and sensors, and also different modulation schemes such as BFSK (binary frequency shift keying) and BPSK (binary phase shift keying).
Sittalatchoumy, R., Kanthavel, R. and Seetharaman, R. (2016) Power Analysis of Sensor Node Using Simulation Tool. Circuits and Systems, 7, 4236- 4247. http://dx.doi.org/10.4236/cs.2016.713348