Title :
Optimum mode-switching assisted adaptive modulation
Author :
Choi, Byoung-Jo ; Hanzo, Lajos
Author_Institution :
Dept. of Electron. & Comput. Sci., Southampton Univ., UK
Abstract :
Adaptive modulation techniques combat fading by employing a suitable modulation mode depending on the instantaneous channel conditions for improving the Bit Error Rate (BER) performance or the average throughput. Based on a generic model of constant-power adaptive modulation, exact closed form expressions of the average BER and the average throughput are derived, when employing square Quadrature Amplitude Modulation (QAM) or Phase Shift Keying (PSK) as the constituent modulation modes, operating over a Nakagami fading channel. The optimum modulation-mode switching levels, achieving the highest possible throughput under the constraint of the average BER, are obtained using the Lagrangian optimisation method. Adaptive modulation employing the optimum switching levels shows a superior performance, while maintaining a constant average BER
Keywords :
adaptive modulation; error statistics; fading channels; mobile radio; optimisation; phase shift keying; quadrature amplitude modulation; telecommunication traffic; time-varying channels; BER performance; Lagrangian optimisation; Nakagami fading channel; PSK; QAM; average throughput; bit error rate; constant-power adaptive modulation; fading; instantaneous channel conditions; mobile communications; optimum modulation-mode switching levels; phase shift keying; quadrature amplitude modulation; time-variant channel; Amplitude modulation; Bit error rate; Channel capacity; Communication switching; Fading; Lagrangian functions; Phase modulation; Phase shift keying; Quadrature amplitude modulation; Throughput;
Conference_Titel :
Global Telecommunications Conference, 2001. GLOBECOM '01. IEEE
Conference_Location :
San Antonio, TX
Print_ISBN :
0-7803-7206-9
DOI :
10.1109/GLOCOM.2001.966300
