Grating Lobes for Enhanced Scattering Intensity in Millimeter Wave Sparse Channels

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Millimeter Wave bands suffer from various channel impairments, such as path loss and blockage sensitivity. Hence, mmWave channels have widely been termed as sparse channels, composed of limited number of rays and clusters. Therefore, analog beamforming architectures become less practical due to its single beam transmission, which can result in link failure due to blockage effects. However, analog beamforming requires very efficient power and energy consumption levels, as compared to digital and hybrid solutions. Hence in this paper, a novel multi-beam analog beamforming transmission technique is proposed that increases the scattering intensity in mmWave sparse channels. This in return allows analog beamforming channels to be increasingly rich-scattering. Namely, grating lobes are deliberately generated for an analog beamformer to increase the scattering intensity in non-line of sight environments, and hence increasing the number of scattering (rays and clusters) in the received signal power delay profile. Simulation results show that channel intensity significantly increases when grating lobes are enabled at one-wavelength antenna spacing, as compared to half-wavelength spacing.