| Popis: |
In this paper, a low cost optical wireless communications link with a data rate of 74 Mb/s at a bit-error ratio of $3.3 \times 10^{-3}$ is demonstrated. The components are all low cost, off-the-shelf parts, including the laser transmitter and silicon solar panel receiver. This performance is achieved by extending the usable bandwidth using analog equalization and digital techniques such as adaptive bit and power loading. Also, the performance of two spectrally efficient modulation schemes, namely direct-current biased optical orthogonal frequency division multiplexing (DCO-OFDM) and pulse amplitude modulation discrete multitone (PAM-DMT) is evaluated and compared. It is shown that DCO-OFDM outperforms PAMDMT because of efficient bandwidth usage with adaptive bit loading and pre-distortion introduced by adaptive power loading. Furthermore, it is shown that PAM-DMT can avoid complex system designs and still achieve comparable data rates to that of OFDM with higher link reliability. |
