On November 12th, 2018, the Asia-Pacific Communications Conference (APCC 2018) was held at Ningbo University. Professor Yang Zhen, President of Nanjing University of Posts and Telecommunications, Director of the National Engineering Research Center for Communication and Network Technology, and Member of the APCC Steering Committee, was invited to give a keynote speech entitled Greening the Smart Cities: Massive Content Delivery via D2D Communications. The report systematically expounded the cutting-edge technology for massive data transmission in D2D systems and demonstrated the latest research achievements in this field made by ourschool.