Extending Linear Constraint Adaptive Array and Null-Space Adaptive Array for Spectrum Sharing Environments

Linear Power Constraint Adaptive Array (LPCAA) and Null Space based Array Antenna (NSAA) were investigated to increase the transmit opportunities of low priority systems under the spectrum sharing condition in [4]. The applicable conditions of LPCAA, however, were limited and the desired signal enhancement by NSAA was not considered in the study. This paper extends LPCAA to cover the case wherein the victim receiver and/or the wanted receiver have multiple antennas. Moreover, desired signal enhancement by NSAA is investigated by using selection or combining possible candidates of weights. Numerical results are given to compare performance in terms of the signal to interference ratio (SIR).