LoRaWAN is one of the most popular low-power wide-area network (LPWAN) technologies. Its network architecture is based on a star-of-stars topology, in which LoRa nodes communicate with gateways that forward payloads to a central server when a packet detection occurs. As the gateway deployment is often not managed by a single entity, their locations across the network can be highly inhomogeneous. To improve the coverage as well as the reliability of LoRaWAN, we propose to use a centralized radio access network (C-RAN) architecture. We introduce an implementation of such an architecture suited for LPWANs which supports popular software-defined radios through interfaces that are compatible with the GNU Radio toolkit. We also show that a centralized processing of baseband signals received by multiple gateways can offer more resilience against fading and allow the utilization of higher datarates for the uplink. Both of these effects reduce the power consumption of LoRa devices which is critical for battery-powered edge nodes.