Abstract
As the fast soaring of modern applications, e.g. high speed business networks, fiber to the home or fiber-wireless integration, the data rate requirement rapidly increases with the years in optical access networks. Due to its cost-effective nature, passive optical network (PON) attracts lots of attention by researchers. Meanwhile, to meet the future data rate requirement, orthogonal frequency division multiplexing (OFDM) is widely investigated and considering as one of the candidate signal formats for next generation PONs. To enhance the performance of PON systems, including channel capacity, bit-error rate (BER) performance, and cost-effectiveness or so on, most of researchers focus on the transmitter design in the central office (CO) or the receiver design at optical network units (ONUs). Therefore, lots of modulation formats and/or receiving mechanisms are proposed for future requirements. However, enhancing the performance via modifying ONUs’ design always requires huge capital expenditures (CAPEX). In this dissertation, we propose two upgrade module concepts. First, in the powered remote node (RN), we can double the channel capacity and user numbers by passive optical polarization de-multiplexing implementation. The other one is a back propagation mitigation function by spatial routing. Both of them are highly compatible with existing wavelength division multiplexing (WDM) PON without any modification of ONUs’ design. System vendors can therefore upgrade the system depending on their marketing targets. In the final chapter, an intensity modulation direct detection (IMDD) system is proposed with uniform downstream receiving performance among subscribers. In general, due to the double side band nature of IM signals, distinct users among different subcarrier in different locations will receive different BER performance caused by radio frequency fading loss. However, it is harmful to ordinary business model. Thus, we propose a multicarrier code division multiple access (MC-CDMA) signal format to uniform BER performance among subscribers ranging from 0 to 100 km. Moreover, the MC-CDMA signals’ performance can be further enhanced by appropriate digital signal processing. Therefore, power budget, which is typically limited by the worst user case, of the proposed MC-CDMA PON is improved with respect to the IMDD OFDM-PON.