Abstract
ANALYSIS OF AWGN, FLAT FADING AND FREQUENCY SELECTIVE CHANNELS USING DAPSK MODULATION TECHNIQUE
Anupam Nema* and Dheeraj Nagar
ABSTRACT
Orthogonal frequency division multiplexing (OFDM) is a modulation technique that is widely used in many wireless communication systems. Now-a-days the requirements of wireless communication are to have high voice quality, high data rates, multimedia features, lightweight communication devices etc. But the wireless communication channel suffers from much impairment. One of them is fading which is due to the effect of multiple propagation paths, and the rapid movement of mobile communication devices. In a typical wireless communication environment, multiple propagation paths often exist from a transmitter to a receiver due to scattering by different objects. So, this is necessary to reduce the problem of fading. In traditional OFDM based on fast Fourier transform (FFT) and discrete cosine transform (DCT) high side lobes are created. Hence, OFDM based on discrete wavelet transform is used in this work. DWT is more flexible in terms of data rate and has much lower side lobes than traditional OFDM. In this work, the performance of OFDM based on DWT is compared with that of traditional OFDM based on FFT and OFDM based on discrete cosine transform (DCT) through the use of differential amplitude phase shift keying (DAPSK) as modulation scheme. These systems are simulated over additive white Gaussian noise (AWGN), flat fading, and frequency-selective channels through MATLAB software. Simulation results reveal that the performance of the proposed system is better than that of the other two systems over all types of channels.
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