A group of modulation schemes for adaptive modulation

Adaptive modulation increases the throughput of a wireless network by adjusting the modulation scheme to the channel status. To have more capacity and more flexibility in using adaptive modulation, our research attempts to find a group of modulation schemes, which includes M-QAM where the number of signal points is not a power of 2, as well as non-squared QAM (or APSK: amplitude and phase-shift keying), so we can have n-bit modulation where n ranges fully from 1 to 6 including half-integer indices. Some recent research has shown that the gap between QPSK and 16-QAM, 16-QAM and 32-QAM, 32-QAM and 64-QAM can be filled smoothly by introducing 12-QAM, 24-QAM and 48-QAM. But the gap between QPSK (4-QAM) and 12-QAM is still an open problem. In this paper we insert 8-ary modulation schemes, and propose 6-ary modulation schemes. Simulation results show that our proposed group can fill smoothly the gap between QPSK and 12-QAM.