Issue link: https://www.e-digitaleditions.com/i/1327492
14 I ICT TODAY There are several options for hybrid cabling infrastructure configurations between the active end devices of the POL architecture: • The main backbone can be composed of SMF between buildings and MMF in the risers inside the buildings. It can be an SMF cable between a main distribution frame (MDF) to intermediate distribution frame (IDF), and an MMF cable from the telecom closet across access layers (i.e., horizontal and drops). In this case, the cabling infrastructure could be retained and the POL architecture would be as follows: OLT SMFmodal splitter SM-MMMMFONT(s). See Figure 7 (A). • Alternatively, the main backbone can consist of MMF between buildings and primarily copper cabling inside the buildings. In this case, to implement the POL, it is necessary to deploy SMF inside the buildings. The POL architecture thus becomes: OLTmodal adapterMMFmodal splitter MM-SMSMFONT(s). See Figure 7 (B). This technology allows simultaneous management of the spatial modes in upstream and downstream operations between SMF and MMF. For the multimode to singlemode configuration (from OLT to ONT) in downstream, the modal adapter converts the fundamental mode from the OLT into the funda- mental mode of the long backbone MMF, and the modal splitter converts the mode from MMF to SMF and splits the signal into the distribution SMFs. For upstream, it is the opposite. The modal splitter converts the SMF's mode from the ONT, recombines the signals into the long backbone MMF, and the remote modal adapter converts the signals from MMF to singlemode for the OLT. As far as the singlemode to multimode configuration (from OLT to ONT) is concerned, the principle remains the same. Downstream, the modal splitter splits the SMF signal from the OLT and converts it to the fundamental mode for distribution MMFs. Upstream, the modal splitter adapts the modes from distribution MMFs and recombines the signals in the backbone SMF. This technique is compatible over a very wide wave- length range (1260 nm - 1650 nm), making it compatible with all existing PON standards (e.g., G-PON, XGS-PON, NG-PON2, GE-PON, 10G-EPON), as well as test and analysis equipment. These modal splitters are available with 2x8, 2x16, and 2x32 coupling rates. In order to be compatible with the FSAN ITU standard-based Type-B PON redundancy—an optional architecture for when the highest level for resiliency is required—2xN splitters should be used. Insertion loss complies with the FIGURE 7: SMF/MMF hybrid POL architecture. Multimode to Singlemode configuration A. B. Singlemode to Multimode configuration