Custom modulation scheme for enhanced voice quality in software defined radio
K. Seshadri Sastry, M. S. Prasad Babu · 2010
Reducing error in a communication system is important to increase its performance. This paper shows how custom ordering in Quadrature Amplitude Modulation (QAM) can be used in an effective manner for voice transmission purposes in a soft radio to give better quality results. This would be compared to the M-ary Gray Coded Mapping Scheme and binary coded mapping scheme. These comparisons apply under some shortcomings like the use of same number of quantization levels i.e. M number of quantization levels for a signal being fed to an M-ary modulator, e.g. using 16 level quantization Along with 16-QAM. It will be shown that for the above mentioned scenario (M quantization levels and M-ary QAM), the custom ordering is superior to normal binary coded QAM and Gray-coded QAM.