Next generation wireless networks ?? Especially the use of milli-microwave bands [Guest Editorial]

The global bandwidth shortage of wireless communications has motivated the exploration of the millimeter wave (mm-wave) frequency spectrum for the next generation wireless communications. Recent advances in RF CMOS technology and high speed baseband signal processing technologies have enabled the extensive research and development of mm-wave wireless communications. The multi gigabit per second data rate of mm-wave system will lead to applications in many important scenarios, such as WPAN, WLAN, back-haul for cellular system. And the frequency bands include 28 GHz, 38 GHz, 45GHz, 60GHz, E-BAND, and even beyond 100 GHz. The propagation and the limitation of the RF circuits design in these frequency bands make the directional antennas be inevitable for mm-wave communications. So, the system design and implementation are challengeable and are much different from the lower bands. The goal of this Special Topic Issue is to explore research and developments related to mm-wave communications to further its state of art.