Self-orienting receiver using rate-adaptive transmission based on OOK formats with memory for optical wireless communications

The simultaneous use of a simple rate-adaptive transmission scheme, based on on-off keying (OOK) formats with memory, and a new self-orienting receiver, alternative to conventional angle diversity techniques, is proposed in order to mitigate the effect of large variations of the signal-to-noise ratio in indoor wireless infrared communications. In relation to the rate-adaptive transmission technique, variable silence periods are used for modifying the statistics of the amplitude sequence regarding the statistics of the message sequence, allowing an increase of the peak-to-average optical power ratio (PAOPR). With regard to the new diversity technique proposed, this is based on giving a self-orienting capability to the receiver optical front-end, thus optimizing link quality parameters. It is applied to links operating at an initial bit rate of 200 Mb/s, providing a signaling rate with a wide dynamic range and a relevant improvement in performance with a gradual complexity in implementation, compared with the scheme proposed and specified in the advanced infrared (AIr) standard by the Infrared Data Association (IrDA), which is based on repetition coding and pulse-position modulation.