In this contribution, four automatic adjustment algorithms for leakage carrier cancellation in radio frequency\r\nidentification (RFID) readers are compared: full search, gradient search, fast and direct I/Q algorithms. Further, we\r\npropose two enhanced adjustment procedures.\r\nFirst, we analytically calculate the performance of the fast adjustment algorithm in the presence of noise and derive its\r\ntheoretical bias. We compare the theoretical results with the numerical results from accompanying simulations.\r\nFurther, we evaluate the performance of these algorithms based on real-world measurements acquired with our RFID\r\ntestbed.\r\nFinally, we propose and discuss the merits of two enhanced adjustment procedures based on the fast adjustment\r\nalgorithm. The fast adjustment procedure with bipolar probing signals achieves the isolation gain of the (much\r\nslower) gradient search algorithm at the expense of a mean penalty of 0.48 dB. We observe that the fast adjustment\r\naided gradient algorithm requires 72% less steps than the gradient search algorithm in our measurements.
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