1)Under the link budget formulla:
path loss= TX power + all gain in link – all loss in link – RX sensitivity.
2)the shadow fading yielded by the building or other obstacles in propagation environment & its distrubuted as log normal.
Thus if the path loss made global mean slope. the variation in this slope up & down called as local mean or log normal fading(shadow fading).
shadow fading differ from urban to suburban to rural as the obstacles cosentration changed.