RF project

I need to buy/design an RF communication system for covering 35 km distance. If I design from scratch will it be feasible to complete in 5-6 months? I need this RF communication module for my project. I have been searching the net but I find it difficult to decide. If I buy an RF module readymade which one would you recommend?
Thanks in advance.

What country? How are you licensing it? What mode? voice, data? data rates? full/half duplex? Line of sight? what sort of terrain?

It is going to be data, half duplex, Line of sight . I do not know about the terrain. I was just asked to get an RF module in the ISM band.

Thanks.

You want 35m or 35km? I think your boss is going to be very disappointed. ISM bands

If your in a line of site aplication and you can literally see the full 35 Km its entirely possible and legal to use small satellite dishes or other similar directional units with special antennae systems to make the typical wireless routers for computers go that far.

Some software tweaks may be needed for the routers and a little research on the specific size, type of dish, and antennae layout is needed as well. But its entirely possible to get slightly modified off the shelf components to work for very long range data systems with reasonable reliability and data transfer capacity.