Small unmanned aerial vehicle (UAV) swarm are characterized by their advantages such as distributed collaboration, functional diversification, high cost-effectiveness, and strong mission adaptability and flexibility. However, as a payload-sensitive aerial platform, small UAVs are constrained by limited in-cabin space and load capacity, and the demand for multi-functionalization, miniaturization and integration of airborne payloads is becoming increasingly strong. In this paper, we first introduce the airborne payloads that enable the basic communication, navigation, sensing, and control functions of small UAV swarms. Then, by review and analyze the integrated design idea through the applications of Integrated Communication and Navigation (ICAN) and Integrated Sensing and Communication (ISAC), we further give the definition of the Integrated Communication-Navigation-Sensing-Control (ICNSC) for small UAV swarm. Finally, the ICNSC system architecture and several key technologies are identified. We hope that this paper will serve as a starting point and provide some useful guidance for future researchers and engineers.