Fade Margin Calculator is used for estimating the link energy parameters and for upstream/downstream speed prognosis.
http://www.infinetwireless.com/Support/antenna_calc
http://www.calculatoredge.com/
http://www.rfglobalnet.com/content/misc/showdoc.asp?docid=%7BFC228779-26E6-4B47-8C9C-73428BFBA44F%7D&enableLeads=0&VNETCOOKIE=NO
http://www.lx.it.pt/cost231/final_report.htm
http://www.pizon.org/radio-mobile-tutorial/index.html