Multiple-input multiple-output options for 60 GHz line-of-sight channels

The 60 GHz band is an attractive candidate for wireless indoor communications as it offers a large amount of license free spectrum. Non-rich scattering situations, which commonly arise at 60 GHz due to the particular propagation conditions, result in relatively high spatial correlation. Spatial multiplexing, a widely considered concept for multiple-input multiple-output (MIMO) communications, can offer large capacity gains if the spatial correlation is low. In this paper, we demonstrate that spatial multiplexing (SM) in conjunction with polarisation diversity is a viable option for 60 GHz line-of- sight (LoS) channels. The performance of the proposed scheme, which uses two antenna elements with orthogonal polarisation at each end of the transmission link, is assessed in terms of capacity. It is then compared to an optimal MIMO beamforming scheme that uses two parallel and identical antennas per link end. Furthermore, the impact of antenna misalignment is investigated.