Enhancing CoAP Group Communication to Support mMTC Over Satellite Networks

Massive MTC (mMTC) is one of the application scenarios that upcoming 5G networks are expected to support. Satellites come into play in mMTC to complement and extend terrestrial networks in under-served areas, where several services can benefit from the adoption of a group communication model. The IETF has specifically standardized the usage of CoAP group communication. However, CoAP responses are still sent in unicast from each single CoAP server to the CoAP client, which results in a substantial traffic load. Such problem becomes more severe in integrated IoT-Satellite networks given the limited bandwidth of the satellite return channel and the large number of IoT devices in a mMTC scenario. To reduce network traffic overhead in group communication and improve the network responsiveness, this paper proposes an aggregation scheme for the CoAP group communication in combination with Observer pattern and proxying. Results obtained by using the openSAND emulator and CoAPthon library corroborate the merit of our optimization in terms of overhead reduction and delay.