The majority of MSOs have an N+X outside plant architecture. Assuming that Fibre to the Premises (FTTP) is the final state of the plant, there are varieties of approaches being considered by each provider to increase bandwidth (BW) in the meantime to compete with fibre-based services. Some are considering a leap directly to a fully passive state (N+0), whereas others are considering reducing amplifier cascades gradually, with a passive state in mind. At Shaw we are contemplating an initial move to N+2, meaning the plant is going to be split directly to an N+2 state from its current architecture.
In this paper an analysis has been carried out to evaluate the potential advantages and disadvantages of going directly to a passive (N+0) architecture versus reducing amplifier cascades to a mid-point (N+2) prior to going to N+0, with a long-term goal of FTTP in mind, in both cases. This is assuming that Full Duplex DOCSIS (FDX) will be developed in a cascaded environment in the near future.
Due to the fact that business as usual (BAU) node splits, based on plant congestion, are not scalable, they have been excluded from the comparison.
Based on the current downstream capacity offerings and projected future growth, the difference in capacity between an N+0 and N+2 plant has been evaluated while taking into consideration the various new technologies that will be deployed in the near future.
Furthermore, a net present value analysis has been provided for the transition from N+2 to N+0.
At its current state, 75% of Shaw’s plant consists of nodes with a longest cascade of 5 or less amplifiers. Depending on when the transition to N+2 or N+0 is projected to occur, a relative estimate for the net present value of the costs has been provided, based on the sample plant selected.
Based on the analysis shown in this paper, assuming that Full Duplex DOCSIS (FDX) is developed in a low-cascade architecture such as N+2, the results show that moving to N+2 --> N+2 FDX --> N+0 FDX has a lower total cost of ownership (TCO), in comparison to moving directly to N+0 FDX.