Smart applications among future cities need quality of service (QoS) for the collection of data from each of their sensor end-points. We propose a multi-hop strategy, over a shared infrastructure, where the network operator offers guaranteed QoS for each application. Even using robust technologies such as the IETF 6TiSCH protocol stack, that take advantage of time synchronization and frequency channel hoping, the end to end performance must be monitored by the operator in order to ensure the best conditions for the collection of data.
We provide simple mechanisms for the monitoring of the two main parameters the clients are expecting : the Packet Delivery Ratio (PDR) and the delays. We evaluate different strategies for the collection of the monitoring information. We demonstrate that the piggybacking gives important capacity gain when the monitoring traffic is well dimensioned. We bound the impact of the size of the application's data payload on the monitoring overhead. We show the advantage of sharing resources among several users in terms of reduction of the monitoring overhead.