Digital communications systems use Multi tone Channel (MC) transmission techniques withdifferentially encoded and differentially coherent demodulation. Today there are two principle MCapplication, one is for the high speed digital subscriber loop and the other is for the broadcasting ofdigital audio and video signals. In this study the comparison of multi carriers with OQPSK and Offset16 QAM for high-bit rate wireless applications are considered. The comparison of Bit Error Rate(BER) performance of Multi tone Channel (MC) with offset quadrature amplitude modulation (Offset16 QAM) and offset quadrature phase shift keying modulation (OQPSK) with guard interval in afading environment is considered via the use of Monte Carlo simulation methods. BER results arepresented for Offset 16 QAM using guard interval to immune the multi path delay for frequencyRayleigh fading channels and for two-path fading channels in the presence of Additive White GaussianNoise (AWGN). The BER results are presented for Multi tone Channel (MC) with differentiallyEncoded offset 16 Quadrature Amplitude Modulation (offset 16 QAM) and MC with differentiallyEncoded offset quadrature phase shift keying modulation (OQPSK) using guard interval for frequencyflat Rician channel in the presence of Additive White Gaussian Noise (AWGN). The performance ofmultitone systems is also compared with equivalent differentially Encoded offset quadrature amplitudemodulation (Offset 16 QAM) and differentially Encoded offset quadrature phase shift keying modulation (OQPSK)with and without guard interval in the same fading environment.
