With the growing use of distributed wireless technologies for modern services, the deployments of dedicated radio infrastructures do not enable to ensure large-scale, low-cost and reliable communications. This PhD research work aims at enabling an operator to deploy a radio network infrastructure for several client applications, hence forming the Internet of Things (IoT).
We evaluate the benefits earned by sharing an architecture among different traffic flows, in order to reduce the costs of deployment, obtaining a wide coverage through efficient use of the capacity on the network nodes. We thus need to ensure a differentiated Quality of Service (QoS) for the flows of each application.
We propose to specify QoS contracts, namely Service Level Agreements (SLAs), in the context of the IoT. SLAs include specific Key Performance Indicators (KPIs), such as the transit time and the delivery ratio, concerning connected devices that are geographically distributed in the environment. The operator agrees with each client on the sources and amount of traffic for which the performance is guaranteed. Secondly, we describe the features needed to implement SLAs on the operated network, and we organize them into an SLA management architecture.
We consider the admission of new flows, the analysis of current performance and the configuration of the operator’s relays.

Based on a robust, multi-hop technology, IEEE Std 802.15.4-2015 on TSCH mode, we provide two essential elements to implement the SLAs: a mechanism for the monitoring of the KPIs, and KAUSA, a resource allocation algorithm with multi-flow QoS constraints. The former uses existing data frames as a transport medium to reduce the overhead in terms of communication resources. We compare different piggybacking strategies to find a tradeoff between the performance and the efficiency of the monitoring. With the latter, KAUSA, we dedicate adjusted time-frequency resources for each message, hop by hop. KAUSA takes into account the interference, the reliability of radio links and the expected load to improve the distribution of allocated resources and prolong the network lifetime. We show the gains and the validity of our contributions with a simulation based on realistic traffic scenarios and requirements.

Keywords: Quality of Service, Wireless Sensor Networks, Multi-hop, Internet of Things, Service Level Agreement, Key Performance Indicators, Reliability, Network Management, Network Monitoring, Scheduling, 6TiSCH