Performance of digital radio systems in co-channel cross-polarized operation

The authors present results on the propagation-channel characteristics of radio-relay systems using orthogonal polarization operation in the same transmission channel. The bandwidth efficiency of digital radio systems can almost be doubled by transmitting and receiving signals on both orthogonal polarizations in the same radio channel. There exists, however, an increased sensitivity of such systems to cross-polarization interference effects. Propagation experiments are described that were performed on two different hops. The copolar attenuation as well as the cross-polar coupling between the orthogonal polarizations were measured quasi-simultaneously. On the basis of the stored channel characteristics the resulting symbol error ratio in digital radio systems is determined analytically. The distribution of symbol error ratio for different system designs is presented