Title :
Power efficiency of OFDM signal amplification with Doherty and extended Doherty transmitters
Author :
Yamao, Yasushi ; Toyama, Yoshikazu ; Umali, Edwin M.
Author_Institution :
Adv. Wireless Commun. Res. Center, Univ. of Electro-Commun., Tokyo
Abstract :
OFDM (orthogonal frequency division multiplex) achieves high spectral efficiency in broadband wireless communications but has poor amplification efficiency due to its large peak-to-average power ratio. This paper presents achievable average power efficiency for the OFDM signal when the Doherty and extended Doherty transmitters are employed. By modelling the envelope of OFDM signal as a Rayleigh-distributed signal, average power efficiency for the OFDM signal is calculated as a function of clipping probability. Numerical calculation results assuming an ideal class-B amplifier and predistortion linearizer show that average drain efficiency of the two amplifiers for a clipping probability of 0.1% are 50.5 and 55.6%, respectively. It is concluded that the extended Doherty amplifier can improve power efficiency by several percents by optimizing the main amplifier contribution ratio alpha.
Keywords :
OFDM modulation; Rayleigh channels; amplifiers; radio transmitters; OFDM signal amplification; Rayleigh-distributed signal; class-B amplifier; clipping probability; extended Doherty transmitters; orthogonal frequency division multiplex; power efficiency; predistortion linearizer; Broadband communication; OFDM modulation; Peak to average power ratio; Power amplifiers; Predistortion; Probability distribution; Radiofrequency amplifiers; Signal processing; Transmitters; Wireless communication; Linear transmitter; OFDM; power efficiency;
Conference_Titel :
Wireless Conference, 2008. EW 2008. 14th European
Conference_Location :
Prague
Print_ISBN :
978-3-8007-3102-2
DOI :
10.1109/EW.2008.4623918
