Guest Editorial: Near-Field MIMO Technologies Toward 6G

Multiple-input multiple-output (MIMO) has been widely adopted into wireless standards and commercial deployments from 4G LTE (long-term evolution) to 5G NR (new radio), as well as IEEE 802.11n/ac/ax (also known as Wi-Fi 4/5/6), etc. Currently, 6G research and development activities are heating up worldwide and 6G wireless technology standariization is expected to start in the middle of 2025. The extreme requirements of 6G set a challenging target for the wireless community, which calls for great efforts in research, standardization, development, and trial activities to realize initial 6G commercialization in 2030. Among the many candidate wireless key technologies, MIMO still plays an important role to boost the system performance, especially with higher frequency bands and larger antenna array sizes. After several decades of research, standardization, and implementation, one important question to answer now is how MIMO continues to evolve.