Technical challenges for high-frequency wireless communication

Recent rapid developments in 4G wireless communication have been motivated by breakthroughs in air interface technology, exemplified by the replacement of WCDMA (Wideband Code Division Multiple Access) with OFDM (Orthogonal Frequency-division Multiplexing). Although the protocol to adopt for 5G HF (High-Frequency) wireless communication—including such matters as waveform, network deployment, and frequency range—has been a controversial issue for a number of years, a common view is that there is a large gap between the rapidly increasing requirements pertaining to traffic capacity and the capabilities of current LTE (Long Term Evolution) networks in terms of spectral and power efficiency. A number of technical challenges need to be overcome in order to bridge this gap. In this paper, by briefly reviewing progress in HF technology, we summarize technical challenges ranging from propagation attenuation and the implementation of circuit devices, to signal processing and the Ka-band to offer feasible reflection on the forthcoming technological revolution.