Next-Generation Optical Access Networks

The main bandwidth bottleneck in today´s networks is in the access segment. To address that bottleneck, broadband fiber access technologies such as passive optical networks (PONs) are an indispensable solution. The industry has selected time-division multiplexing (TDM) for current PON deployments. To satisfy future bandwidth demands, however, next-generation PON systems are being investigated to provide even higher performance. In this paper, we first review current TDM-PONs; we designate them as generation C. Next, we review next-generation PON systems, which we categorize into C+1 and C+2 generations. We expect C+1 systems to provide economic near-term bandwidth upgrade by overlaying new services on current TDM-PONs. For the long term, C+2 systems will provide more dramatic system improvement using wavelength division multiplexing technologies. Some C+2 architectures require new infrastructures and/or equipment, whereas others employ a more evolutionary approach. We also review key enabling components and technologies for C+1 and C+2 generations and point out important topics for future research.