Motivated by the rapid deployment of various applications based on connected objects, we propose in this paper an approach to differentiating Packet Delivery Ratios in LoRa Wide Area Networks (LoRaWAN). This type of network is simple to deploy and operate at the expense of loose commitments in terms of quality. To overcome this shortcoming, we propose an access control method of isolating clusters of devices and meeting differentiated PDR objectives. Simulation results show that the proposed technique performs better in terms of PDR than known heuristics for parameter allocation and achieves high level of intra-cluster fairness, at the expense however of decreasing the maximum cell range.