Performance comparison of LMS, diagonalizer and bootstrapped adaptive cross-pol cancellers for M-ary QAM

In microwave radio communication networks, the transmission capacity can be doubled by using orthogonally polarized quadrature amplitude modulated (QAM) carriers. The orthogonally polarized waves can suffer degradation due to carrier-to-cross-polarization interference (C/XPI). Particularly during multipath fading, such degradation would become intolerable. Different canceller structures are proposed to mitigate the effect of cross-polarization. Among these are the diagonalizer, the LMS, and the bootstrapped cancellers. The bootstrapped canceller has been implemented in different applications such as satellite dual-polarized communication, tactical communication, and QAM microwave radio. The probability of error performance of the bootstrapped cross-polarization canceller (BXPC) is studied and compared to the performance of other cancellers. The performance of the three cancellers is compared numerically for the 16 QAM with r=-10 dB, and -5 dB. It is shown that the LMS canceller outperforms the diagonalizers, particularly when the cross-coupling is high. Except for a very low signal-to-noise ratio, the BXPC outperforms the LMS with 64 QAM, more that with 16 QAM