Cross Polarization Interference Cancellation (XPIC).
Microwave having XPIC capabilities effectively double the potential capacity of a Microwave Path.
It allows the assignment of the same frequency to both the vertical & horizontal Polarization on a Path.
Where available frequencies are limited then it is possible to assign the same frequency twice on the same path using both Polarizations.
Using standard Microwave equipment from any of the major manufacturers, if a full block of eight frequencies were available for a 6 GHz Lower band path then eight frequencies could be assigned in each direction on the path, four per polarization.
Using equipment with XPIC capability, sixteen frequencies may be assigned each way on the same path (eight per polarization).