Practical scheme to enable MIMO communications in distributed antenna systems for efficient indoor coverage

Multiple input multiple output (MIMO) has been considered as one of the key enablers of the broadband wireless communications. In this paper, we describe the several practical deployment cases where repeater links (or relay links) such as distributed antenna system (DAS) can act as keyholes to degenerate the rank property of MIMO communications. In order to get MIMO spatial multiplexing (SM) gain even in those cases, we propose a practical scheme which uses simple converter in the devices in repeater links. By using the simple converters, MIMO SM is possible even over the indoor DAS with single cable. Seeing the characteristics of indoor channels, the proposed scheme is expected to enhance the system capacity significantly in a cost-effective manner.