Laboratory experimental results of an adaptive modulation/TDMA/TDD for wireless multimedia communication systems

This paper reports laboratory experimental results of a time division multiple access/time division duplex (TDMA/TDD) based adaptive modulation system to verify feasibility and its usefulness for future wireless multimedia communication systems. The developed system employs a symbol rate and modulation level controlled adaptive modulation in which the modulation scheme is selected from full-rate 64-ary quadrature amplitude modulation (64 QAM), full-rate 16 QAM, full-rate quaternary phase shift keying (QPSK), 1/2-rate QPSK, 1/4-rate QPSK, 1/8-rate QPSK and no transmission according to the expected channel condition for the transmitted signal. The experimental results confirm that the developed system is very effective in achieving high quality and high bit rate transmission of around 1 Mbit/s without any special anti-frequency selective fading techniques even under frequency selective fading conditions with its d delay spread of less than 250 ns and f_d of less than 10 Hz