Best practices for installing large scale wireless connection

Hi there,

The company that I work for are facing some issues regarding wireless connection, the main problems are now are:

• Wireless interference
• Network jamming

The wireless interference is happening because there are many routers in the company, and I think all the wifi radios are working on the same channel (with different SSID names), so what could be the best practice for this type of issue?

Network jamming, it's happening because the Head office is located near a presidential place, and most probably they have network jammers. I don't know if we can avoid this, but if there were any suggestions, please tell me.

Thanks in advance!