More links to understand wireless

http://www.mobile-review.com/

For good understanding of all kinds of Protocols:
http://www.protocols.com

http://www.umtsworld.com/technology/overview.htm- This has a good overview tutorial on 3G UMTS

http://www.3g-generation.com/http://www.three-g.net/http://www.three-g.net/-
More useful links for 3G UMTS

http://www.privateline.com/Cellbasics/Cellbasics.html- For some cellular wireless basics

http://www.gsmworld.com/- Some general information on GSM

http://www.3gpp.org/- This has all the GSM/GPRS/EDGE/UMTS specifications

http://www.mobile-review.com/print.php?filename=/articles/2003/gsm-phones-en.shtml has very good illustration of basic concepts related to wireless and wireline communication system

http://www.privateline.com/PCS/PCS2.htm

http://www.privateline.com/wireless.html

http://www.cnp-wireless.com/cellular.html

www.gsmworld.com