Title :
Variable rate DFE-QAM and OFDM systems for maximum capacity in multipath frequency selective fading channels
Author :
Aguayo-Torres, M.C. ; Entrambasaguas, J. Tomas ; Ruiz, F. ; Baños, J.
Author_Institution :
Dept. Ingenieria de Comunicaciones, Malaga Univ., Spain
Abstract :
Two adaptive modulation systems to counteract frequency and time selective fading in digital transmission over multipath radio channels are analyzed: a single carrier QAM system with decision feedback equalization (DFE-QAM) and an OFDM system. In order to maintain a target BER, an adaptive modulation level of the single-carrier in the DFE-QAM system, or each subcarrier in the OFDM system, which tracks the channel fluctuations is used. The spectral efficiencies of both systems are compared to the theoretical channel capacity. Various impairments such as inaccurate or delayed channel estimation and a limited-rate feedback channel have been considered
Keywords :
OFDM modulation; adaptive modulation; channel capacity; decision feedback equalisers; digital radio; fading channels; land mobile radio; multipath channels; quadrature amplitude modulation; BER; adaptive modulation systems; channel capacity; channel estimation; channel fluctuations; decision feedback equalization; digital transmission; limited-rate feedback channel; maximum capacity; multipath frequency selective fading channels; multipath radio channels; single carrier QAM system; spectral efficiencies; subcarrier; variable rate DFE-QAM; variable rate OFDM; Adaptive systems; Bit error rate; Channel capacity; Decision feedback equalizers; Digital modulation; Fading; Fluctuations; OFDM modulation; Quadrature amplitude modulation; Target tracking;
Conference_Titel :
Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th
Conference_Location :
Amsterdam
Print_ISBN :
0-7803-5435-4
DOI :
10.1109/VETECF.1999.797136
