Tightness of Semidefinite Programming Relaxation to Robust Transmit Beamforming with SINR Constraints

<table>Second eigenvalue <svg height="8.125" id="M440" style="vertical-align:-0.1638pt" version="1.1" viewbox="0 0 8.3374996 8.125" width="8.3374996" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
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</svg> versus target SINR <svg height="12.175" id="M441" style="vertical-align:-3.56265pt" version="1.1" viewbox="0 0 8.6374998 12.175" width="8.6374998" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path d="M478 372q0 -39 -31 -97t-61 -98t-78 -98q-45 -55 -73 -102q-13 -79 -13 -197q-11 -11 -43.5 -25.5t-53.5 -15.5l-15 17q5 35 26 101.5t47 123.5q8 72 -1.5 174.5t-37.5 178.5q-14 37 -29 37q-20 0 -67 -65l-25 21q37 60 73 90.5t63 30.5q47 0 72 -112q13 -56 17.5 -141.5
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Mathematical Problems in Engineering

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Figure 3

Figure 3: Tightness of Semidefinite Programming Relaxation to Robust Transmit Beamforming with SINR Constraints 