The Research And Implementation Of The FH-OFDM System Based On FPGA

OFDM has high bandwidth-efficiency and the ability in coping with frequency selective fading or narrow-band interference,which makes it suitable for high speed wireless transmission.It will be the key technology of the 4^th generation mobile communication system in the future.Frequency hopping technology possesses the characteristics of anti-interference and has the ability of secrecy and multiple access network.And it has a wide application prospects.FH-OFDM system which combined frequency-hopping technology and OFDM technology could not only support high-speed data transmission but also strengthen the anti-interference ability of the system.Study FH-OFDM system has the great value of practical application for the development of communication technology.A FH-OFDM modulation system based on OFDM technology and frequency hopping technology was designed and implemented by mainly programing with hardware language(Verilog,VHDL),assisting with IP Core and Schematic in ISE 6.2. OFDM modulation system mainly includes constellation mapping,IFFT translation. The frequency-hopping system which based on DDS can change its frequency by changing its frequency control word.Finally,the OFDM modulation system and frequency-hopping system are connected by Schematic to constitute FH-OFDM modulation system.All the simulations of the paper are completed with ModelSim SE 6.0.After all the subsystem's simulation and synthetizing correctly by XST,the wave of FH-OFDM modulation system is correctly got.Study the development platform of FPGA,and load programmes to FPGA with XC3S400-4PQ208.Two common hardware description languages,Verilog and VHDL,are applied in the models of m sequence,S/P conversion,constellation mapping,DDS,frequency control word,frequency division. In this way,Migration can be taken in FPGA chips from all producers.The simulation and test results show that the design can correctly implement the models of OFDM modulation and frequency-hopping modulation.And the two parts are connected by multiplier.Accordingly,FH-OFDM modulation system is implemented.Some useful conclusions are gained by analyzing the test results.