FPGA-implemented 8-carrier OFDM modem set

WECHSLER, A.; LIBERATORI, M. C.; CASTIÑEIRA MOREIRA, J.

Congreso; Information Processing and Control Workshop; 2017

UNMDP

In this paper, an 8-carrier Orthogonal FrequencyDivision Multiplexing modulator/demodulator set is developed.The system is implemented on a Field Programmable Gate Arrayplatform, using VHSIC Hardware Description Language. An 8-Quadrature Amplitude Modulation square-shaped constellationis applied, in conjunction with an eight point IFFT/FFT (in themodulator/demodulator side, respectively), to achieve the desiredorthogonal frequency multiplexing. Data is transmitted to, andreceived from the Field Programmable Gate Array, usingUniversal Asynchronous Receiver/Transmitter serialcommunication.At the modulator side, 24 data bits are received by the FPGA.The device processes this sequence, and computes the eightcorresponding time-domain components that make up oneOrthogonal Frequency Division Multiplexing symbol. At thedemodulator side, the eight time-domain components arereceived, and 24 binary data points are estimated. A 2?scomplement fixed-point representation is used to representdifferent variables and results. The length of the integer andfractional parts is changed in every operation performed, inorder to avoid losing precision.The system was tested generating many random binary pointswith a PC and modulating them with the designed hardware inthe Field Programmable Gate Array. Adding noise to data isperformed through simulation of Gaussian and Rayleighchannels with the PC. After being affected by the correspondingchannel, data are demodulated by the hardware system. Finally,Binary Error Rate simulations allow us the study of theperformance of the scheme.