Not all wireless communication systems are using line of sight configuration,
For point-to-point communications (esp. microwave comm.) use line of sight, Broadcasting uses isotropic radio propagation (also HFSS/DFSS)
most wireless comm. network are able to work both LOS and NLOS schems. for example in mobile communications, when you are in a building, you have a NLOS communication with the BS.
both digital and analog telecommunications can work in these two schemes because this problem is related to the transmission signal models in different area