Capacity Optimized Line-of-Sight HAP-MIMO Channels for Fixed Wireless Access

This paper proposes a design approach to construct a high rank multiple-input multiple-output (MIMO) channel matrix in line-of-sight (LoS) propagation environment, when high altitude platforms (HAPs) are involved. This approach enhances the performance of systems, which can not utilize the MIMO gain introduced by independent and identically distributed (i.i.d.) Rayleigh fading channels or require the existence of a strong LoS signal. Geometrical design recommendations are introduced, considering Ka and V frequency bands licensed for broadband communications through HAPs. In these high frequency bands, the rain has a significant effect on the quality of the link and applications, such as Fixed Wireless Access (FWA), are feasible. The results show the potential capacity gain of the optimized LoS-HAP-MIMO architecture, under clear sky and rain conditions.