Research On Channel Coding And Modulation With Software-Defined Radios

As a new structure for wireless communication, software defined radio (SDR)technology uses software programming to implement various radio functions.Compared to traditional hardware structure, it has greater flexibility. This paper buildstwo Coded Orthogonal Frequency Division Multiplexing (COFDM) wirelesscommunication systems based on the software defined radio platform composed ofthe Universal Software Radio Peripheral (USRP) and a general purpose computer,thus verifies algorithms of channel coding and decoding, modulation anddemodulation actually.Aiming at low reliability of data transmission, this paper designs and implementsa Turbo coded OFDM wireless communication system. This system adopts burstpackets transmission mode. At the transmitter, Turbo codes with excellentperformance is used to encode the data being transmitted. At the receiver, soft-inputsoft-output Max-Log-MAP iterative decoding algorithm is applied to obtain thecoding gain. Simulation and test results show that, adopting COFDM technology caneffectively combat fading and noise, reduce the frame error rate, thus improve datatransmission reliability.Aiming at low flexibility of the digital video broadcasting-terrestrial (DVB-T)system, this paper implements a DVB-T transmitter and a DVB-T receiver based onSDR structure. At the transmitter and receiver, the USRP acts as a radio frequencyfront-end. Channel coding and decoding, modulation and demodulation, videodecoding and displaying are all implemented on the general purpose computer.Verification and test results show that, this system is in line with the specification ofDVB-T, enables real-time signal broadcasting and receiving.In summary, this paper implements a Turbo coded OFDM system and a DVB-Tsystem, then tests the data-transfer in actual channel environment, which provides amore flexible method for algorithms design, verification and evaluation.