Reliable and scalable data acquisition from IoT domains

In this work we have examined aspects of reliable and scalable acquisition of big data from IoT domains. We have modeled the performance of CoAP enabled cross proxy IoT gateway towards the domain of CoAP enabled IoT devices. We focused on maintaining freshness of cache records at the proxy while maintaining low delay and low energy communications. We show that non-confirmable CoAP mode works well with acknowledged mode of 6LoWPAN/IEEE 802.15.4 cluster and that high delay and timeout values proposed in CoAP can be avoided. To support data freshness limit imposed by CoAP we have included sensor replicas which report the same variable. We have shown that addition of sensor replicas together with proactive cache update can ensure low record outdate probability while combination of proactive and reactive cache update can still have low outdate probability while limiting energy expenditure of nodes.