IEEE Communications Surveys and Tutorials

I welcome you to the fourth issue of the IEEE Communications Surveys and Tutorials in 2021. This issue includes 23 papers covering different aspects of communication networks. In particular, these articles survey and tutor various issues in “Internet Technologies,” “Network Security,” “Network Virtualization,” “Optical Communications,” “Vehicular and Sensor Communications,” and “Wireless Communications.” A brief account for each of these papers is given below.