This Project deals with a small Unmanned Aerial Vehicle (UAV)Communication system. The considered distance between UAVs is 100 m to 10 km. These small UAVs are usually used for civil purposes like fire fighting, for farmers etc. This report represents the modem architecture for a small UAV radio network, which works with flexible transmission data rates (62 kbps to 744 kbps)by using an Orthogonal Frequency Division Multiplexing (OFDM) technique with adaptive resource allocation. It includes the instructions and architecture of an Fast Fourier Transform (FFT) processor for a single radix - 2 butterfly engine. The architecture is being modeled in Altera Hardware Descriptive Language (AHDL). For logic synthesis we have used Altera functions. An OFDM technique with adaptive modulation and codiing is used to readily achieve variable data rates and to provide a multipath resistant solution. We also investigate different FPGAs characteristics including memory, multiplexers and logic cells, to identify a low complexity and low cost solution. A Cyclone II FPGA is considered likely to implement the processing required for small UAV communication with the ground stations and between UAVs.