Impedance Variation Detection at MISO Receivers

Techniques have been proposed to estimate unknown antenna impedance due time-varying near-field loading conditions at multiple-input single-output (MISO) receivers. However, it remains unclear when a change occurs and estimation becomes necessary. In this letter, we address problem by formulating as hypothesis test. Our contributions include deriving generalized likelihood-ratio test (GLRT) detector decide if the has changed over two groups of packets. This GLRT formulation leads novel optimization problem, but propose binary search based algorithm solve efficiently. derived enjoys better detection false alarm trade-off compared with well-known, reference in simulations. As one result, more transmit diversity significantly improves accuracy given rate, especially slow fading channels.