Spatial multiplexing algorithms of cognitive base-stations

The existing cognitive network can not provide the spatial sectors for a cell, since the base-station (BS) has one omnidirectional antenna. Thus it is impossible for a base-band channel to be shared by several mobile stations(MSs) with one omni-directional antenna. To solve the problem, this paper proposes the spatial multiplexing algorithms for transmitter and receiver of cognitive BS. In the proposed scheme, the cognitive BS has a uniform circular array (UCA) with 8 elements, it can provide five nearly orthogonal sectors for MSs, and a base-band channel can be shared by 5 sectors, but the MS has one omni-directional antenna only, and simple transmitter and receiver. The experimental results verify that the proposed algorithms are able to increase the cellular capacity to nearly 5 times with low co-channel interference, and the co-channel interference also can be canceled by LDPC codec.