Power reduction techniques for multiple-subcarrier modulated diffuse wireless optical channels

In this paper, two novel techniques are proposed to reduce the average optical power in wireless optical multiplesubcarrier modulated (MSM) systems, namely in-band trellis coding and out-of-band carrier design. Data transmission is confined to a bandwidth located near DC. By expanding the signal set and coding over the increased degrees of freedom, an in-band trellis coding technique achieved an average optical power reduction up to 0.95 dBo over conventional MSM systems while leaving the peak optical power nearly unaffected. With a symbol-by-symbol bias, the received DC level can be detected to provide a degree of diversity at the receiver. In this manner, an additional average optical power reduction up to 0.50 dBo together with a peak power reduction of 0.46 dBo is achieved. Moreover, the unregulated bandwidth available in wireless optical channels is exploited and out-of-band carrier signals are designed outside the data bandwidth to reduce the average optical power. Average optica...

• Type: Journal
• Year: 2008
• Where: TCOM
• Authors: Weiwei Kang, Steve Hranilovic
• Keywords: Average Optical Power, Optical Power Reduction, Out-of-band Carriers, TCOM 2008