Chapter 5 Strategies For System Performance Improvement Using Multi-Polarized Arrays

This paper gives a theoretical best polarization and SINR. The optimal polarization results in higher SINR than either matching the polarization of the desired signal or nulling the interfering signal. 86 In [5.9] a multi-polarized array that consists of four pairs of crossed dipoles is considered. The array was used with and without a flat-backed corner reflector as shown in Fig. 5-5. Figure 5-5. The multi-polarized adaptive array investigated in [5.9] Mutual coupling effects are modeled using a method of moments computer code. With the corner reflector the array has a half power beamwidth of approximately 42 in elevation and 21 in azimuth. Sidelobe levels are-10 dB in elevation and-5 dB in azimuth. For identical desired and interfering signal polarization states, with the desired signal at broadside, the array provided an SINR improvement of 20dB for a 3 difference in azimuth or elevation angles, and 30 dB for a 10 difference. For a 15 difference in polarization angle, the array provides 30 dB SINR improvement without the reflector. The same SINR improvement can be achieved for a 10 difference in polarization angle if the reflector is used. SINR was significantly degraded in cases with 2 or 3 interferers. In [5.10], the LSCMA algorithm and variations are proposed for cross polarized interference cancellation (XPIC). Real and multitarget variations of the algorithm are y z y z 87 considered. Digital and hybrid implementations are shown. Two scenarios were simulated, one for intrasystem interference and another for intersystem interference. In the first scenario two 16 kHz MSK signals having a 45 degree difference in polarization tilt angle coexist on the same frequency. Each signal has a 20 dB SNR and 23dB Eb/No. Accounting for polarization mismatch, SINR in 3 d B..