Abstract-High splitting, optically amplified, passive optical networks (SuperPONs) are investigated in terms of redundancy provision and protection mechanisms. Options for redundancy, including the important special case of dual homing, are detailed, and it is determined as to which of these options (duplication of the feeder and first distribution section, and + 1 protection of the optical amplifiers in the amplified splitter) would be required to be provided to all attached users to facilitate appropriate availability of the basic telephony service. The distributed amplified splitter dual homing solution is found to outperform the single amplified splitter solution in terms of its survivability. The protection mechanisms necessary to automatically switch to the redundant provision are discussed and it is seen that with the aid of suitable regular precautionary procedures protection switching can generally be provided rapidly ( 50 ms). Finally an availability, and cost versus availability, study confirms the aforementioned redundancy assessment for fiber-to-the-home (FTTH) implementations, but shows fiber-to-the-curb (FTTC) as needing additional redundancy.
Next-generation high-speed passive optical network (HS-PON) transceivers supporting 25, 50 and 100 Gb/s are under the early stage of their standardization process. One key aspect of this process is the choice of the best modulation format. To this end, performance comparisons among several modulation formats against different physical constraints have been presented in literature and are still being carried out. In our contribution, we performed an exhaustive analysis on the impact of transceivers electrical frequency response shape on the performance of 2-levels pulse amplitude modulation (PAM-2), 4-levels PAM (PAM-4), electrical and optical duobinary modulation formats with adaptive equalizer at the receiver side. We show by means of numerical simulations that the specification of the typically used -3dB bandwidth is not sufficient, since also out-of-band electrical frequency response specifications (such as the -20dB bandwidth) has a huge impact on the performance of the analyzed modulation formats. The normalized graphs given at the end of the paper in terms of -3dB and -20 dB bandwidths can thus be useful for the design of the next generation of HS-PON transceivers.
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