Application of MIMO theory to the analysis of broadband fixed wireless access diversity systems above 10GHz

In this paper, a novel approach to the analysis of BFWA diversity systems has been presented which is quite different and more communications-oriented than the traditional propagation-based ones. In particular, it is shown that a double CSD BFWA system operating at frequencies above 10 GHz and under rain fades can be seen as a special case of a 2times2 MIMO system. After pointing out the differences and establishing the exact relationship between the two systems, well-known results available in the MIMO literature were applied for the performance analysis of BFWA diversity systems. This paper particularly looked at the single-user capacity of such a system in both cases that the channel is known and unknown to the transmitter. An interesting outcome of the analysis is that there is no significant capacity gain due to feedback, which further implies that no additional complexity in terms of feedback links is useful to a BFWA diversity system. This can be ascribed to the high correlation of rainfall medium. Furthermore, simulation results have shown that, in case of unbalanced BFWA diversity systems, exclusive power allocation is the optimal choice at low SNR, whereas at high SNR, equal power allocation is the optimal one. This paper hopes that this relationship between the two systems can be used to obtain additional useful insights into the design and analysis of BFWA diversity systems by drawing on the vast body of MIMO literature that is currently available