LOW DISTORTION TRANSMISSION OF 802.11a/n SIGNALS IN AMPLIFIEDRADIO OVER FIBRE LINKS WITH MODULATOR BIAS OPTIMIZATION

摘要

In this work, we study the propagation of an IEEE802.11a/n compliant signal over an analog optical linkemploying a Mach-Zehnder modulator, an Erbium dopedfibre amplifier and 10 km of standard fibre. We show that,when the bias of the modulator is controlled in order tomaximize the received RF power at the end of the link,the link linearity can also be improved. This is due to theinteraction between the distortion caused by the Mach-Zehnder and the fibre nonlinearities. We simulate andmeasure the link intermodulation distortion (ID3) as afunction of the modulator bias, showing in which condi-tions it is possible to simultaneously minimize the ID3and maximize the link gain. Also, we show that the errorvector magnitude, an important quality factor of OFDMIEEE 802.11a/n signals, can greatly benefit from the im-proved link linearity. Thus, the bias optimization allowsfor both higher power and higher quality transmissionwith respect to standard quadrature biased links.