Indoor SDMA capacity using a smart antenna base station

In this paper we consider the capacity of a set of portable stations sharing a single indoor radio channel. The stations communicate with a base station which is equipped with a smart antenna operating in multibeam SDMA/FDMA mode, Both theoretical models and measured data from an experimental testbed are presented. The experimental system operates at 1.86 GHz and uses an 8 element circular antenna array. This system was built at the Communications Research Laboratory at McMaster University. The paper focuses on the static TDMA network capacity of this system. In particular, we explore the value of performing dynamic slot assignment when constructing the SDMA/TDMA frames. Slot assignment algorithms are introduced which are capable of increasing static system capacity under non-ideal propagation situations. In all cases, optimal SINR beamforming is used to determine the performance of the system. The results presented give clear insights into the network capacity possible in such systems and indicate the value of dynamic slot assignment under time division duplex operation. The results can also be used to motivate the design of media access protocols for these types of networks.