Access network technology is evolving at an ever-increasing rate and the devices that are deployed in the outside plant may need to outlast multiple generations of change. In addition, as demand for bandwidth increases and the number of subscribers per node decreases, more access nodes are deployed, causing the cost per subscriber to increase. This requires an architecture that maximizes invested capital yet allows for flexible adoption of new technology.
This paper proposes a road map of ‘Grey Optical Aggregation’ (GOA) for the outside plant that will lower the cost of distributed access networks. As a rule of thumb, grey optics work well when distances are short and fiber is plentiful. Colored optics, like those used in DWDM systems, are best when the opposite is true. Also as a general rule, and comparatively, grey optics are inexpensive while colored optics are not. The challenge to the HFC industry is to optimize the use of each technology, deep in the plant, so as to maximize the fiber asset while keeping costs at a minimum. There are many ways to do this and hence there are many shades of grey optics.
The GOA architecture begins with lower cost grey optical nodes that are aggregated together at an RPD node location, allowing the subtended nodes to share the capacity of the 10Gbps DWDM Ethernet link.
The road map culminates in a low powered, environmentally hardened ‘Switch On A Pole’ (SOAP) that multiplexes multiple 10Gbps grey Ethernet optics and leverages Coherent Optical links of 100Gbps and beyond to extend the headend into the outside plant as close to customer as possible. This allows the operator to pivot between or use multiple access technologies at the very end of the network easily.
In this paper, we begin with a description of grey optics and the benefits and tradeoffs relative to DWDM optics. We will then will describe the process of incorporating grey optics aggregation in DAA networks and demonstrate the benefits of the GOA architecture. We then discuss operational aspects of this new architecture and the various upgrade options. We then describe the SOAP architecture and provide a stable road map towards supporting ever growing demands of the future while utilizing multiple access network technologies such as PON, DOCSIS and Ethernet.