Title :
Bit-interleaved coded modulation for hybrid RF/FSO systems
Author :
He, Ben ; Schober, Robert
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of British Columbia, Vancouver, BC, Canada
fDate :
12/1/2009 12:00:00 AM
Abstract :
In this paper, we propose a novel architecture for hybrid radio frequency (RF)/free-space optics (FSO) wireless systems. Hybrid RF/FSO systems are attractive since the RF and FSO sub-systems are affected differently by weather and fading phenomena. For example, while 60-GHz RF systems are susceptible to rain, fog is detrimental to FSO systems. We show that a hybrid system robust to these impairments is obtained by joint bit-interleaved coded modulation (BICM) of the bit steams transmitted over the RF and FSO sub-channels. An asymptotic performance analysis reveals that a properly designed convolutional code can exploit the diversity offered by the independent sub-channels. Furthermore, we develop code design and power assignment criteria and provide an efficient code search procedure. The cut-off rate of the proposed hybrid system is also derived and compared to that of hybrid systems with perfect channel state information at the transmitter. Simulation results show that hybrid RF/FSO systems with BICM outperform previously proposed hybrid systems employing a simple repetition code and selection diversity.
Keywords :
convolutional codes; diversity reception; interleaved codes; modulation coding; optical communication; asymptotic performance analysis; bit-interleaved coded modulation; code search procedure; convolutional code; free-space optics; hybrid RF-FSO wireless systems; perfect channel state information; power assignment criteria; radio frequency; repetition code; selection diversity; Convolutional codes; Fading; Interleaved codes; Modulation coding; Optical modulation; Optical transmitters; Performance analysis; Radio frequency; Rain; Robustness; 60¿GHz RF systems; Free-space optics (FSO); bit-interleaved coded modulation (BICM); diversity; hybrid RF/FSO systems;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2009.12.080396