By wirelessly connecting billions of devices such as sensors, vehicles, and machines, the ubiquitous connectivity to IoT (Internet-of-Things) will fundamentally change the way we interact with one another and with the physical world. On the other hand, the massive connectivity, uneven information payload, severe cost and power constraints, and diverse QoS and service needs of IoT applications also pose significant challenges to existing design principles of wireless systems. To address such challenges, we aim to develop fundamentally new access protocols and transmission technologies specifically for the next-generation massive IoT-centric wireless applications, to achieve low-overhead and low-cost communications at high efficiency and low-latency. In this talk, we will share some of our recent work that will help us to achieve this goal.