Power consumption analysis of a wireless 1K-pixel visual sensor node: to compress or not?

The applicability of wireless sensor networks is usually limited by the lifetime of sensor nodes having a restricted energy supply. In case of visual sensors, the amount of collected data increases significantly, resulting in a high power consumption by the transmitter. Efficient video compression algorithms reduce the amount of data which has to be sent. On the other hand, video codecs are known to be computationally demanding. It is unclear whether or not spending more power on compression and less on transmission increases battery lifetime, especially if processing is performed on a general-purpose reprogrammable microcontroller. This paper presents the power profile of a very low-resolution wireless visual sensor node. The node executing a predictive video coding engine is compared against the system transmitting raw data. Both setups are examined while capturing static and dynamic video content in strictly controlled environment conditions. Experimental results prove that video compression executed on the microcontroller prior to the wireless transmission reduces the power consumption of the sensor mote.