A: Yes, you do normally need line of sight from both ends of every fixed wireless link in the 2.4 GHz ISM band - and in all other microwave bands, for that matter. Base stations are deployed on towers or the roofs of high buildings, which have a commanding view over adjacent terrain. In some cases, trees and other buildings may cause obstructions, which can be overcome using a mast extension at the user's location. Some new technologies, such as Alvarion's 2.4GHz high power subscriber unit and their OFDM 3.5 GHz technology, promise the ability to operate in non-line-of-sight environments provided there is sufficient multipath signal received via reflections. | 
