Waveforming: An Overview With Beamforming
By leveraging the natural multipath propagation of electromagnetic waves, waveforming is proposed as a promising paradigm that treats each multipath component in a wireless channel as a virtual antenna to exploit the spatial diversity. As the most commonly known waveforming technique for wideband systems, the time-reversal (TR) signal transmission produces a TR resonance by coherently combining multipath energy distributed on virtual antennas, and thus boosts the received signal strength while reducing interference. The wideband waveforming is, in many ways, similar to the multiple-input multiple-output (MIMO) beamforming, where multiple antennas are deployed to imitate a multipath transmission when the bandwidth is limited. In this paper, we provide an overview of recent advances on the wideband waveforming, including massive multipath effect, optimal resource allocation, wireless power transfer and secrecy enhancement for secured communications, and compare with the corresponding counterparts of traditional MIMO beamforming.