Measuring energy consumption for RESTful interactions in 3GPP IoT nodes

As the Internet of Things (IoT) evolves to encompass ever increasing quantities of smart devices, sensors and other smart objects, attention must be paid to considering what kinds of wireless networks should be employed, and the data transfer protocols to be used to allow communication among these entities. It is highly important that energy consumption for communication remains as minimal as possible. In this paper we present power consumption measurements in end devices, when REST-based resource retrieval is performed with HTTP and CoAP over 3GPP EDGE, HSPA and LTE networks. Our findings are based on actual measurements taken over the radio interface of a mobile handset in live cellular networks, and show that for a few transactions of small packet sizes, HTTP performs comparatively well in terms of power consumption. Also, power consumption is lowest in the handset when EDGE is used, but an LTE network with operator assisted power savings approaches power consumption levels seen with EDGE. Finally, for sessions consisting of large number of transactions, we show that using CoAP over the WebSocket protocol results in significantly less power consumption compared to HTTP.