Performance evaluation of rate-adaptive transmission techniques for optical wireless communications

The performance evaluation of different rate-adaptive transmission techniques for indoor unguided optical links is presented. Here, the superiority of the adaptive environment based on the use of variable silence periods and on-off keying (OOK) formats with memory has been corroborated if compared to other rate-adaptive techniques also used in this kind of system. Classical convolutional and rate-compatible punctured convolutional (RCPC) coding have been considered. A new hybrid RCPC scheme, with a puncturing matrix based on the insertion of variable silence periods, is proposed, achieving better bit-error rate (BER) results than conventional RCPC codes. On the other hand, OOK formats with memory have also been analyzed from the point of view of run-length limited (RLL) codes, comparing their performance with the HHH(1,13) code proposed and specified in the very fast infrared (VFIr) standard by the Infrared Data Association (IrDA). Finally, OOK formats with memory have revealed a greater increase of the peak-to-average optical power ratio (PAOPR). PAOPR has shown to be a very efficient parameter for evaluating the suitability of different rate-adaptive transmission techniques to the peculiar characteristics of wireless infrared channels.