Hi Oussama,

This type of question is very hard to answer without seeing your environment and doing a proper site survey. That being said. I have tried to add some information to help with your decision. I have stayed with mostly Autonomous type references but if you want to go with a more managed solution we can point you to a LWAPP or Lightweight design. Without seeing anything I might suggest an AP like the 1240 series which can be ordered as an Autonomous AP but upgraded to LWAPP should you move in that direction down the road. It also has flexible antenna options :) If you wanted something a little cheaper with built in antennas try the 1100 series;

http://www.cisco.com/en/US/products/ps6521/

http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_data_sheet0900aecd8045690f.html

Wireless Site Survey FAQ

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_q_and_a_item09186a00805e9a96.shtml

Cisco Aironet Wireless Access Points Solution Overview

http://www.cisco.com/en/US/products/ps6521/prod_brochure0900aecd8035a015.html

Antenna reference guide;

http://www.cisco.com/en/US/products/hw/wireless/ps469/products_data_sheet09186a008008883b.html

I have attached some good "getting started" type Security docs)

Wireless LAN Security White Paper

http://www.cisco.com/en/US/netsol/ns340/ns394/ns348/ns386/networking_solutions_white_paper09186a00800b469f.shtml

Five Steps to Securing Your Wireless LAN and Preventing Wireless Threats

http://www.cisco.com/en/US/netsol/ns340/ns394/ns348/ns386/networking_solutions_white_paper0900aecd8042e23b.shtml

WLAN Security considerations (Part of WLAN SRND Guide)

http://www.cisco.com/application/pdf/en/us/guest/netsol/ns178/c649/ccmigration_09186a00800d67eb.pdf

Wireless LAN Security Solution

http://www.cisco.com/en/US/netsol/ns339/ns395/ns176/ns178/netqa0900aecd801e3e59.html

Hope this helps! Please let us know.

Rob