Base Station Cooperation Null-Beamforing for Spectrum Sharing between Next Generation Cellular and Fixed Satellite Systems

摘要

Base station cooperation (BSC) transmission (i.e. multicell transmission, cooperative transmission) has been shown to significantly increase average and cell-edge throughputs compared to conventional single-cell transmission. In this paper, we extend BSC techniques to cooperatively force full or partial nulls at victim receiver antennas (e.g. Fixed Service Satellite Earth Station or ES) while providing cooperative stream transmission to intended receivers (e.g. Next Generation Cellular user terminals). First, we express null-beamforming (NB) spectrum sharing as a constrained optimization problem where the objective is to maximize capacity or coverage of the intended system and the constraints are the BS transmit powers and intersystem interference levels. We then introduce single-cell null-beamforming (SC-NB), linear BSC-NB, and non-linear BSC-NB algorithms. Finally, we test these algorithms on a 2×2 MIMO, 2-cell, IMT-Advanced physical layer model and show their significant increases in capacity and coverage over a power-control scheme and single-cell null-beamforming schemes.