**4. Conclusions**

This chapter presented a study of the transmission performance of UWB signals over two different optical based networks. Firstly, a low-cost RoF solution based on a VCSEL and two high performance POFs for assessing the UWB signal transmission performance was presented. Experimental measurements of packet error rate (PER) and minimum transmitted powers to achieve the maximum allowed PER showed that it is possible to have a viable transmission at data rates of 480 Mbps, 200 Mbps and 53.3 Mbps over 100, 150 and 200 meters of PF-GI-POF, respectively, preceded by a 1 meter wireless link. The two PF-GI POFs have diameters of 62.5 *μ*m and 120 *μ*m with bandwidth distance products higher than 1 GHz·Km.

It was shown that the PF-GI-POF attenuation, and not its bandwidth, is the dominant factor limiting the fiber link length. Therefore, the PF-GI-POFs are a viable solution for transporting UWB signals. In particular, the larger core GI-POF with 120 *μ*m diameter may find applications in both the home and office environments where easiness of installation and handling are vital.

Finally, a performance analysis of both the slope efficiency and responsivity of a R-EAM transceiver for different wavelengths, optical powers and bias points was presented. In particular, the performance of RoF transmisssion with zero bias transceivers was evaluated for the UWB ECMA-368 standard. The optimum operation point was found to be the biasing the transceivers for maximum link SNR, using a high optical input power at 1560 nm wavelength. Although a zero bias may seem limitative, the R-EAM can be optimally biased using a small battery, which can last for several months, allowing the BS to operate almost as a passive device.
