This paper presents a design of DFT-spread OFDM system applied to an underwater acoustic channel. It does not only combine all the advantages of a conventional OFDM system but also reduces the peak-to-average power ratio of the transmit signal. Besides, the scheme spreads the information over several subcarriers as a result of the application of an additional DFT operation and leads to a diversity gain in a frequency-selective fading channel, which is one of the many challenges of communicating data through an underwater acoustic channel. Simulation results show that our proposal possesses good bit-error-rate performance. The system has been tested in a real underwater acoustic channel-the experimental pool in Xiamen University. The experimental results show that the DFT-spread OFDM system can achieve better results than a simple OFDM system in a benign underwater channel.
In recent years cooperative diversity has been widely used in wireless network, and Orthogonal frequency division multiplexing (OFDM) is a key technique of multi-carrier transmission to meet high data rate requirement of wireless communication. The aim of this project is to combine the technology of OFDM with cooperative diversity techniques, in this project, we have done simulation in matlab and compare the performances of the system while the cooperation node employs AF cooperative scheme contrast with DF cooperative scheme. The simulation results show that the OFDM system with Cooperative Diversity has a better performance when the cooperation node employs DF cooperative scheme.
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