Spectral efficiency and optimal base placement for indoor wireless networks

In this paper, we address the problem of optimizing the spectral efficiency of cellular indoor wireless networks by adjusting the location and power of the base-stations. Focusing on the downlink, we derive general network access criteria for mobiles on the indoor floor for systems that employ omnidirectional antennas and adaptive antennas arrays at the base-stations, in order to show and explain the advantages of the use of spatial diversity. Multiple access capability measures that depend only on energy are defined for both schemes. They are then used as the cost function for the solution to the optimal base-station placement problem, for a single-frequency system. Both continuous and combinatorial approaches have been applied to the solution of the optimization problem, and near-optimal solutions have been obtained. We show that the use of adaptive arrays yields greater capacity when increased cell-area overlap is allowed. The optimization methods, channel prediction methods, and a graphic user interface are parts of an integrated software environment that we developed in support of our investigation and which is described