The popularity of Internet of Things (IoT) has resulted in increased deployments of Low Power Wide Area (LPWA) technologies for both commercial and private services due to their performance and cost advantages. Although Low Power Wide Area Networks (LPWANs) have the advantages of low power consumption, wide coverage, low-cost and scalability, they generally have lower data rates and lower reliability, thus limiting their suitability for a wider range of industrial use cases such as process control and high data rate multimedia applications. To overcome this, LPWA technologies can be integrated into 5G, a flexible, scalable, agile and programmable mobile communication system. In this paper, we provide a survey on LPWAN-5G integration focusing on the main integration challenges and potential solutions. We firstly compare popular licensed and unlicensed LPWA technologies, and then introduce the 5G architecture and enabling technologies for LPWAN-5G integration. Finally, we discuss in detail the challenges and potential solutions of LPWAN-5G integration, covering all the important aspects including hybrid architecture, security, mobility, interoperability between LPWANs, and coexistence with other wireless technologies. From our analysis, it can be seen that LPWAN-5G integration tends to evolve from access network to core network.INDEX TERMS 5G, cellular, converged core network, the Internet of Things, low power wide area network.