Hierarchical selection diversity combining architecture

This paper proposes a hierarchical selection diversity (HSD) scheme whereby a large array is split up into multiple groups, with the best antenna (in the SNR sense) being selected in each group. The set of selected antennas is then combined using maximal-ratio combining. As opposed to generalized selection combining (GSC), which imposes no restriction on the set of selected antennas, the proposed scheme allows considerable simplification of the RF switching stage while still offering excellent performance, rivaling that of full MRC at the same array size. The performance is analytically characterized, and an exact closed-form expression is provided for the BER.