DWT Based OFDM with DAPSK Modulation for Power Line Communication Systems

C The idea of using power line systems for energy transmission as well as for data transmission is an alternative to wireless and wired communication systems. Communicating over the existing power line is quite advantageous in terms of cost. Power line systems are subject to frequency selective fading due to intense ambient noise and multipath transmission in the transmission environment. To overcome this problem, a multi carrier modulation idea has been introduced. In this paper, the performance of discrete wavelet transform based differentially encoded amplitude - phase shift keying modulated orthogonal frequency division multiplexing systems is investigated on power line channel. As the power line channel has impulsive noise effect, the time and frequency localization of the wavelet transform improves the performance. In addition, since the cyclic prefix is not used in wavelet transform based systems, the bandwidth efficiency is high. Simulation results show that the proposed structure is robust to interference and multipath effects, and that no channel estimation is needed because differential modulation is used