Now people are used to the high speed of modern cellular communication connection, but behind the high-speed transmission, there are countless innovations and research and development work that spend a lot of time. Kiran Mukkavilli, senior director of engineering and technology at Qualcomm Technologies, was personally involved in the work and understood the difficulties involved. He put forward some basic ideas of orthogonal frequency division multiplexing (OFDM) radio waveform, which helps to make high-speed wireless data transmission possible. OFDM is the core technology of 4G and 5G, and also one of the most important fields of modern wireless technology. Mukkavilli has worked for Qualcomm for nearly two decades. His research fields cover 3G, 4G, 5G and MediaFLO (Qualcomm's first mobile broadcasting technology), as well as various aspects of ground positioning technology. He leads the positioning research and development work of the entire Qualcomm Technologies Company, and is currently engaged in 5G Advanced related research, which will lay the foundation for 6G. In the interview, Dr. Mukkavilli talked about his work in the fields of OFDM and MediaFLO, and what excited him most about 6G. In the field of communication, we often hear the word "OFDM". Can you explain what OFDM is? OFDM (orthogonal frequency division multiplexing) means "orthogonal frequency division multiplexing". The basic idea is that through ingenious physical methods and accurate timing, multiple different subcarriers or radio waves can be overlapped in the same communication link at the same time, and they can be separated by frequencies that do not interfere with each other. Thanks to this revolutionary idea, it is possible to expand the capacity of cellular communication networks on a large scale since the 3G era. OFDM has become the basis of high-speed communication in 4G and 5G networks. Cellular base stations and mobile phone modems use OFDM modulated radio waves to communicate with each other. Can you share your early work related to OFDM? How does it affect today's cellular communications? I was engaged in this project when I started my career at Qualcomm. At that time, the world was focusing on the transition from 3G to 4G. There have been early projects to study OFDM and how to use it to support different applications. At that time, we were studying how to implement mobile broadcasting on mobile phones, that is, to broadcast to all users in a network. We know that OFDM is a feasible way, but there are many questions to answer and solve. In this project, we developed a systematic approach to the use of OFDM in mobile wireless systems and provided solutions to multiple fundamental challenges. For example, I start from designing pilot signals to understand the characteristics of wireless links, including the number of signal propagation paths and the strength of each path, which is called channel estimation. A good and updated channel estimation is essential to support high data transmission rates on wireless channels, and pilot signals are used to estimate wireless channels that change over time. I put forward a method based on periodic configuration and