Title :
Linearly precoded or coded OFDM against wireless channel fades?
Author :
Wang, Zhengdao ; Giannakis, Gwrgios B.
Author_Institution :
Dept. of Electr. & Comput. Eng., Minnesota Univ., Minneapolis, MN, USA
Abstract :
Orthogonal frequency division multiplexing (OFDM) converts a dispersive channel into parallel subchannels and thus facilitates equalization. But when the channel has nulls close to or on the FFT grid, OFDM faces serious symbol recovery problems. As an alternative to various error-control coding techniques that have been proposed to ameliorate the problem, we linearly precode (LP) symbols before they are multiplexed. We identify the maximum achievable diversity order for iid or correlated Rayleigh fading channels and also provide design rules for achieving maximum diversity gains with LP-OFDM. Simulated performance comparisons of LP-OFDM with existing block and convolutionally coded OFDM alternatives favor LP-OFDM in a HiperLan2 experiment
Keywords :
OFDM modulation; Rayleigh channels; channel coding; digital radio; dispersive channels; diversity reception; error correction codes; linear codes; probability; synchronisation; wireless LAN; FFT grid; HiperLan2; LP-OFDM; coded OFDM; correlated Rayleigh fading channels; dispersive channel; diversity order; equalization; error-control coding; iid channels; linearly precoded OFDM; maximum diversity gains; orthogonal frequency division multiplexing; parallel subchannels; performance; symbol recovery; wireless channel fades; AWGN; Convolution; Convolutional codes; DSL; Digital video broadcasting; Dispersion; Diversity methods; Fading; OFDM; Transmitters;
Conference_Titel :
Wireless Communications, 2001. (SPAWC '01). 2001 IEEE Third Workshop on Signal Processing Advances in
Conference_Location :
Taiwan
Print_ISBN :
0-7803-6720-0
DOI :
10.1109/SPAWC.2001.923899
