Signaling Technique for Free Space Optics
Amrita Chakraborty1, Avinash Gaur2
1Amrita Chakraborty Electronics And Communication, RGPV, Bhopal Gyan Ganga College of Technology, Jabalpur (M.P.) India.
2Avinash Gaur, Electronics And Communication, RGPV, Bhopal Gyan Ganga College of Technology, Jabalpur (M.P.) India.
Manuscript received on May 27, 2012. | Revised Manuscript received on June 15, 2012. | Manuscript published on June 30, 2012. | PP: 201-203 | Volume-1 Issue-5, June 2012. | Retrieval Number: E0471061512/2012©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: A new efficient method to implement orthogonal frequency division multiplexing (OFDM) on intensity modulated direct detection (IM/DD) channels is presented and termed auto-correlated optical OFDM. It is shown that a necessary and sufficient condition for a band limited periodic signal to be positive for all time is that the frequency coefficients form an autocorrelation sequence. Instead of sending data directly on the subcarriers, the autocorrelation of the complex data sequence is performed before transmission to guarantee non-negativity. In contrast to previous approaches, auto-correlated optical OFDM is able to use the entire bandwidth for data transmission and does not require reserved subcarriers. Using a sub-optimal design technique with 1024 subcarriers, auto-correlated optical OFDM has a better BER than the existing techniques.
Keywords: Auto-correlation, IM/DD,OFDM.