Abstract
This paper proposes a novel design technique for irregular shaped cells in the high altitude platforms (HAPs) cellular system. This technique is based on dividing the coverage area into a grid of small pixel spots and the desired cell is obtained by grouping some pixel spots to give the desired cell shape. These spots are formed with narrow and low sidelobe level beams using concentric ring array (CRA) to reduce the cochannel interference as well as improving the resolution of the design. The desired cell pattern is converted into a spatial mask that selects the desired pixel spots with a proper pre-weight smoothing function. The proposed cell design technique will optimize the cell shape according to the user distribution and behavior in the covered area and consequently is expected to reduce the frequent handoff and signaling traffic of location updating from moving users. Simulation results show that a cell with any irregular shape can be formed with as low as 40 dB sidelobe level using Gaussian CRA. (C) 2013 Elsevier GmbH. All rights reserved.