This paper proposes areas of improvement for Low Power Wide Area (LPWA) solutions. After recalling the rationale of these systems, it summarizes the main challenges of existing solutions and proposes various improvements at PHY and MAC layer that were investigated in context of the EPHYL project. NB-IoT and LoRa were mostly considered in the analysis of existing techniques, while proposals for improvement address both waveform design and resource allocation strategy. We propose as well introduction of new paradigm such as network coding to benefit of the sparse characteristic of some LPWA use cases. Some of the proposals are validated experimentally in the FIT/CorteXlab environment, offering to the research community a framework to experiment and compare their improvements of LPWA systems.