FPGA implementation of a people counter for an ultra-low-power Wireless Camera Network node

Wireless Camera Network (WCN) nodes differ from traditional Wireless Sensor Network (WSN) nodes because of the huge amount of data generated by the sensing element. In order to be able to operate on batteries for a long period, a WCN node needs to extract the information contained into an image and synthesize it into a short message that can be wirelessly transmitted with a limited amount of power. Unfortunately, this approach typically brings the power consumed by the processing unit at the same level as the transceiver, known to be the major source of power consumption in WSN. Thus, there is the need to design efficient algorithms that can be implemented on low-power devices. In this paper we propose the implementation of a Dijkstra-based people counting algorithm for ultra-low-power FPGAs. The developed code has been integrated on the prototype of a WCN node that consumes as little as 5 mW.