Hmm, actually quite interesting. One article says that the maximum transmission power for GSM900 is about 0,25W. And one of the FCC pages says 0,234W and the frequency is 2.4G. IMO the transmission power should be much lower when we are using that free 2.4G band. Hmm, do we have Wimax here? Actually the mobile version of Wimax is working from 2 GHz to several GHzs. And the transmission power (0.234W) could be something like that and there is no need for the line of sight component.