CoAP Endpoint Identification - A Protocol Extension for Crowd Sensing in the Mobile Internet

Independent from a specific contract on what the Internet of Things (IoT) actually is, the various definitions have at least one thing in common, i.e. The inclusion of sensor data which originates from a vast amount of (resource constraint) sensing devices. Recently, the IETF came up with the full specification of the Constrained Application Protocol (CoAP) [1], a lightweight alternative to HTTP. As such, CoAP enables the provisioning of actual measurements via Web services. The number of smart phones in the world hit 1 billion units in 2013 and is expected to hit 1.7 billion units in 2017 and clearly, smart phones can be considered IP enabled sensing devices. However, they often suffer from resource constraints in terms of bandwidth. Furthermore, the mobile Internet often uses network address translation (NAT) due to the lack IPv4 addresses and the insufficient network coverage of IPv6. Both make it impossible for smart phones to host a Web service that is fully integrated with the Internet. Additionally, smart phones are often assigned new IP addresses because of network changes. This paper introduces CoAP Endpoint ID as an extension to the core CoAP protocol to deal with IP address changes within an ongoing message exchange. Furthermore this paper depicts the integration of this extension with a scalable realization concept for an IoT that overcomes both, the bandwidth and the NAT issue.