Solutions: Architectures
Passive HFC Architecture
Aurora's first implementation using next-generation optical networking equipment
was an evolutionary progression of the traditional HFC architecture to meet the demands for
increased services (e.g., bandwidth-hungry, revenue-generating services such as high-speed
Internet access, Video-On-Demand, Interactive TV and telephony). Aurora's Passive HFC architecture
includes Aurora's patented, integrated digital return technology and continues to enable network
operators to install lucrative business-to-business Ethernet services cost effectively. The
Passive HFC architecture is depicted in the graphic below.
Enlarged View
Aurora's Passive HFC architecture drives fiber deeper (increasing the distribution
reach of fiber optic networks) by subdividing the typical HFC node service area into Fiber
Service Areas of 50-200 homes. The optical node locations are optimized to eliminate all RF
amplifiers and most power supplies. This architecture dramatically increases both the bandwidth
to each subscriber and the reliability of the network at construction costs similar to
traditional HFC, while reducing ongoing operating and maintenance expenses.
Services are delivered to subscribers via a combination of 1550nm broadcast and
narrowcast technology. Return subscriber signals are digitized at the node and multiplexed with
Ethernet traffic from business customers for transport at 1310nm. In the return transport
network, the nodes are linked together in a daisy-chain configuration sharing a common digital
return transmission channel. This daisy-chain configuration permits the concatenation of all
digitized signals from each node of the chain into the same return transmission channel for
conversion to a DWDM 1550nm wavelength, if required, and transport from the last node in the
chain to the hub. At the hub, all of the DWDM wavelengths are multiplexed together for
transmission back to the headend.
Migration to ''Best Fit''
Architectures continue to evolve and migrate down different paths. Aurora's optical
network equipment provides the greatest flexibility to design and deploy ''best fit'' solutions
to implement these migrating architectures. The chart below shows several of the more popular
topologies that are commonly deployed with Aurora equipment.
Enlarged View
Fiber Deep-HFC (optical node with zero RF amplifiers) uses fiber's reach advantage to
increase service area sizes and further extend networks. As municipalities continue to expand,
Fiber Deep used in conjunction with field-based hubs are providing more bandwidth per subscriber for
longer distances.
Fiber on Demand™ (HFC with additional dedicated FTTH for
Ethernet and other digital services) allows service providers to overlay fiber on an existing coax
deployment from the optical node to individual subscriber premises on an as-needed basis. Providers
can use existing plant facilities and augment their services by installing a parallel optical network.
Other architectures focus on hub-centric, distribution-based enhancements such as D2WDM
and development of field-deployed hubs (or ''Virtual Hubs'') (the chart above also showing such a field
hub distribution architecture) and push more functions into a centralized headend. The complete optical
product lines described on this CD allow ''one stop shopping'' to design and build the architectures
described.
With Aurora's award-winning Virtual Hub (as noted in the center of the above chart, and
based on the VH4000 node housing platform), up to 24 optical nodes can be supported with as few as
2 fibers, serving up to 20,000 homes and removing the need for real estate and facilities.
Developments in Access Platforms
The latest advancements in architectures have been in an optical network's
subscriber access where access platform variants have each been optimized for different service
area demands. Aurora Networks' optical node provides proven customizable solutions for scaling
the bandwidth-per-subscriber, matching service level requirements, supporting multiple technologies
(LcWDM™, DWDM, CWDM), and deploying a wide variety of access architectures (e.g.,
traditional HFC, segmented-node HFC, Fiber Deep, Fiber to the Home, PON). The diagram below shows
the bandwidth per HP for each of the more common access platform architectures.
Enlarged View
| 
