Measurements of energy consumption and execution time of different operations on Tmote Sky sensor nodes

RNDr. Moslem Amiri, Ph.D.

Master's thesis

Abstract:

In order to provide WSNs with security, additional energy is required. Since sensor motes usually have limited source of energy, it is important to balance the level of security and energy consumption. To find this trade-off, we need to know the amount of energy consumed by different components on sensor motes while running security algorithms. In this work we perform some measurements to estimate the energy consumption and execution time of different operations on a Tmote Sky sensor mote. This device is equipped with CC2420 radio transceiver, MSP430 microcontroller, and ST M25P80 flash memory. To make the measurements, first we explore different methods to that end, and then set up the best possible configuration in order to perform precise measurements. For the transceiver, since CC2420 is an IEEE 802.15.4 compliant radio, we investigate different frame structures and CSMA/CA medium access mechanism of this standard to discover the overhead of channel acquisition, header and footer of data frame, and transfer reliability during packet transmission. Next, the implementation of this standard in TinyOS, a popular operating system widely used in WSNs, is taken into consideration. Then we measure time and energy needed to send and receive a 1-byte data payload, an 11-byte acknowledgment frame, and an 18-byte header and footer of the data frame in TinyOS. We also compute the energy consumed during channel acquisition and listening operations. This data makes the fixed and incremental components of a linear equation to estimate the power consumed during every packet transmission. Finally, we input this per-packet power consumption in a mathematical model which estimates the lower and upper bounds of routings in the network. We categorize different simulators currently available in order to propose the function and structure of a new potential simulator. Due to the fact that radio operations are the most expensive ones in sensor motes, this proposed simulator focuses on radio rather than internal operations. The microcontroller of Tmote Sky, MSP430, has several power states with varying power draws. We measure energy consumptions in different power states of this microcontroller. We also compute the energy consumption and time needed to write/read one byte of data from/to ST M25P80, the external flash memory of Tmote Sky.

Keywords

CC2420 radio, execution time, IEEE 802.15.4, lifetime bounds, measurements, MSP430 microcontroller, power consumption, simulator, ST M25P80 flash memory, Tmote Sky sensor mote, wireless sensor network

Language used: English

Date on which the thesis was submitted / produced: 31. 5. 2010

Thesis defence

• Date of defence: 28. 6. 2010
• Supervisor: RNDr. Andrij Stecko, Ph.D.
• Reader: prof. RNDr. Václav Matyáš, M.Sc.

Masaryk University

Faculty of Informatics

Master programme / field:
Informatics / Embedded Systems (eng.)