Hello Shahid! Security in 802.16e is much better than in WiFi. You now that developers try to make very secure system.As I now they used a lot of experiences from both wireless and wire network. I wish to learn it deeply, becouse it seems very interesting aspecially from the practise point of view :) Can you recomend me sites, books to learn. Now I'm learning PHY and MAC very deeply, becouse of my work. It you have questions in these parts, you can as me.