A Wavelet Multiplexing to Reduce Phase Noise Effects in OFDM based DVB-t

Orthogonal Frequency Division Multiplexing (OFDM) is a highly recommended multiplexing/modulation scheme for high data rate communications due to its high spectrum efficiency and robustness against Inter Symbol Interference (ISI). The OFDM is based on dividing the available spectrum into narrow band orthogonal subcarriers and modulating data on each subcarrier. Due to long symbol period, OFDM system is more sensitive to phase noise of the oscillator compared to single carrier systems. The Phase noise of oscillators used in the transmitters & receivers results in two effects, Common Phase Error (CPE) & Inter Carrier Interference (ICI). These effects results in increasing SNR requirement at the receiver to achieve certain BER. The design & simulation of OFDM based DVB-t system with wavelet multiplexing & demultiplexing and analysis of phase noise effects on BER is presented in this paper. The performance of simulated DVB-t system is analysed by considering SNR requirement to achieve certain BER in the presence of oscillator instabilities on AWGN & mobile radio channels. The modelled Wiener phase noise is generated for different 3dB bandwidths of noise spectrum. The simulation results shows that, the SNR required to achieve a bit rate of 10-2 in wavelet multiplexing is around 6dB lower as compared to FFT counterpart. The result also reveal that PAPR is also less, however wavelet multiplexing computational intensive.