TDMA-Based Adaptive Modulation with Dynamic Channel Assignment for High-Capacity Communication Systems

This paper proposes a time-division multiple-access (TDMA)-based adaptive modulation scheme with dynamic channel assignment (AMDCA) to achieve high-capacity communication systems under dynamically changing propagation path and traffic conditions. The proposed method measures the received carrier-to-noise plus interference power ratio (C/(N + I)) of each TDMA slot to search available slots as well as to find out the optimum modulation parameters for each terminal, thereby effectively combining the effect of mitigating both spatially distributed electric field strength variation by the slow adaptive modulation and spatially and temporally distributed traffic variation by the dynamic channel assignment (DCA). Computer simulation confirms that the proposed AMDCA system can achieve approximately three times higher system capacity than the conventional fixed channel assignment (FCA) using QPSK. Index Terms--Cellular systems, dynamic channel assignment, quadrature amplitude modulation, slow adaptive modulation systems, time-division multiple-access.